Table of engine and its systems faults (Chevrolet Lanos T150)

The crankshaft does not turn with the starter

List of possible faults	Diagnostics	Methods of elimination
The battery is discharged	The voltage at the battery terminals with the consumers switched off is below 12 V. When the starter is turned on, a crackling sound may be heard from under the hood	Charge the battery; if it does not charge, replace it. The engine can be started by "lighting" it from another car's battery
Decrease in battery capacity	The voltage at the battery terminals with the consumers switched off is more than 12 V, but when the starter is switched on it drops below 6-8 V. At the same time, a crackling sound may be heard from under the hood	Charge the battery with a small current (no more than 1 A); if the capacity is still insufficient, replace the battery. The engine can be started by "lighting" it from another car's battery
Oxidation of battery terminals and wire terminals, loose fit	When the starter is turned on, the voltage in the on-board network drops much more than at the terminals of the battery. At the same time, a crackling sound may be heard from under the hood	Tighten the terminals, clean the contact surfaces, lubricate them with technical petroleum jelly
Engine or attachments seized	Check if the engine crankshaft, power steering pump pulleys, alternator and air conditioning compressor are rotating	Repair engine, generator, replace power steering pump, air conditioning compressor
The starter drive gear or flywheel ring gear teeth are damaged	Inspection after removing the starter	Repair or replace starter, replace flywheel
The starter circuit is faulty: fuse EF3 is faulty, the wires are damaged, the ignition switch contacts do not close	When turning the ignition key to the "START" position, the starter solenoid does not operate (no click under the hood). Check if +12 V is supplied to the control contact of the traction relay	Replace faulty: fuse EF3, wires, ignition switch contact group
The starter traction relay is faulty: short circuit or break in the pull-in winding, jamming of the relay armature (anchor misalignment, surface contamination, corrosion, etc.)	When turning the key to the "START" position, the traction relay does not operate (no click under the hood), but +12 V is supplied to the control contact of the traction relay. Remove the relay, check its operation	Replace the faulty traction relay
Oxidized contacts of the traction relay or wires, poor contact "mass"	When the starter is turned on, a click is heard under the hood, but the starter anchor does not rotate. Check the resistance of the "battery - starter" circuit with an ohmmeter, including the "ground" wire. If the circuits are in good condition, remove the starter and check the operation of the traction relay by supplying power to it directly from the battery	Tighten the wire tips, crimp the terminals. Replace the faulty traction relay
Open or short circuit in the holding winding of the starter traction relay	When the starter is turned on, a cracking sound is heard from under the hood. The voltage on the battery is within normal limits. An open or short circuit in the holding winding of the starter traction relay is checked with an ohmmeter or by excessive heating of the relay	Replace the starter solenoid relay
Starter collector burnout, brushes sticking or heavily worn	The starter anchor does not rotate or rotates slowly. First, make sure that the traction relay is working properly, for which you can supply power to the starter contact bolt directly from the battery, bypassing the relay	Replace worn out components or starter
Open or short circuit in the starter armature winding	The starter anchor does not rotate or rotates slowly. First, make sure that the traction relay is working properly, for which you can supply power to the starter contact bolt, bypassing the relay. The serviceability of the winding is checked with an ohmmeter or by darkening of the insulation	Replace the anchor or starter
Freewheel clutch slipping	When the starter is turned on, the anchor rotates, the flywheel is stationary	Replace the clutch or starter

Loud noise when starting the starter

List of possible faults	Diagnostics	Methods of elimination
The starter is mounted on the cylinder block at an angle, its fastening is loose, or the cover on the drive side is broken	Inspection	Tighten the bolts securing the starter to the cylinder block; if the cover is broken, replace the starter
Excessive wear of starter bearings or journals of drive shaft and anchor. Wear and damage to planetary gear teeth	Inspection after disassembling the starter	Replace the planetary gear or starter
The ring gear rotates on the flywheel	When the starter is turned on, the toothed ring rotates, the flywheel and crankshaft are stationary. A squealing, howling sound is heard from the clutch housing	Replace flywheel
The teeth of the starter drive gear or (more often) the flywheel ring gear are worn out	Inspection after removing the starter	Replace the drive gear, starter or flywheel
The gear does not disengage from the flywheel: the drive lever is jammed, the freewheel clutch spring or the starter traction relay is weakened or broken, the clutch is jammed on the splines of the drive shaft or the traction relay armature, the ignition switch is faulty (ignition switch contacts do not open)	Check whether the voltage is removed from the control terminal of the starter relay when the ignition key is released, whether the key returns to the "ON" position. The opening of the ignition switch contacts can be checked with an ohmmeter. If the voltage on the starter traction relay disappears when the ignition is turned off, remove and disassemble the starter for inspection	Replace the starter solenoid or starter assembly, ignition switch contact group

The crankshaft is turned by the starter, but the engine does not start

List of possible faults	Diagnostics	Methods of elimination
There is no fuel in the tank	By fuel level indicator and fuel reserve indicator	Add fuel
The battery is discharged	The crankshaft is turned by the starter very slowly. The voltage at the battery terminals with the consumers switched off is below 12 V	Charge the battery; if it does not charge, replace it. The engine can be started by "lighting" it from another car's battery
Decrease in battery capacity	The crankshaft turns very slowly. The voltage at the battery terminals with the consumers switched off is more than 12 V, but when the starter is switched on it drops to 6-8 V	Charge the battery with a small current (no more than 1 A); if the capacity is still insufficient, replace it. The engine can be started by "lighting" it from another car's battery
Oxidation of the terminals of the wires on the battery terminals, their loose fit	The crankshaft is turned by the starter very slowly. When the starter is turned on, the voltage in the on-board network drops much more than at the terminals of the battery	Tighten the terminals, clean the contact surfaces, lubricate them with technical petroleum jelly
Unreliable connection of electrical circuits of engine control and power supply systems	Check the connection of the electrical connectors of the wire harnesses, the reliability of the contacts in the terminal blocks of the wires	Fix the faulty connections in the connectors
Increased resistance to rotation of the engine crankshaft: scoring on shafts, bearing shells, parts of the cylinder-piston group; deformation of shafts; the engine oil has frozen; generator, power steering pump, air conditioning compressor are jammed	The crankshaft is turned by the starter very slowly If the weather is cold and the engine worked steadily and without any extraneous noise the day before, the reason for the increased resistance to rotation is most likely solidified oil. In this case, try starting the engine using another battery. After starting, do not allow the engine to run at high speeds and watch the low oil pressure indicator: if it lights up, immediately stop the engine for 1-2 minutes so that the thickened oil has time to drain into the pan If you hear extraneous noises when starting or running the engine, check the free rotation of the pulleys of the power steering pump, generator and air conditioning compressor	If there is any extraneous noise in the area of the block or cylinder head, repair the engine Use engine oil according to climate conditions Replace the generator, power steering pump, air conditioning compressor
Malfunction in the ignition system	Check spark plugs for spark formation. If there is no spark, the cause may be faulty instruments and low voltage circuits (fuse F15, ECU, primary winding of ignition coil) or high voltage (secondary winding of ignition coil, high-voltage wires)	Check the ignition system circuits and devices. Replace the faulty fuse, device and wires. Ensure contact in the electrical circuits
The timing belt is broken or the belt teeth are cut off	Inspection after removing the front upper timing belt cover	Replace the timing belt. Check the compression in the cylinders
Defective spark plugs	Check spark plugs for spark formation	Replace the spark plugs
The valve timing is out of order	Check the alignment of the marks on the crankshaft and camshaft pulleys	Set the correct relative position of the shafts. Check the compression
The ECU, its circuits or the crankshaft position sensor (less often the coolant temperature sensors and air temperature sensor) are faulty	Check if +12 V is supplied to the ECU, the crankshaft position sensor circuit, and if the sensor itself is damaged. If the temperature sensor is faulty, the ECU may incorrectly calculate the fuel mixture composition	Replace faulty constant power supply fuse F5, ECU, sensors, wires
The absolute air pressure sensor or its circuits are faulty	Check the sensitivity of the absolute air pressure sensor	Replace the faulty absolute air pressure sensor
Fuse EF2 blown	Check the fuse	Eliminate the cause of the blown fuse. Replace the faulty fuse
The fuse of the power circuit of the fuel pump relay F17 has blown, the following are faulty: the pump power circuit, its relay or the pump itself	When the ignition is turned on, the pump does not sound. Check the fuse. Apply power directly from the battery to the pump terminals	Replace the blown fuse, clean the contacts, crimp the wire ends, replace the faulty relay, pump
The fuel filter is clogged, water that got into the fuel system has frozen, and the fuel lines are deformed	When turning the crankshaft with the starter, there is no smell of gasoline coming from the exhaust pipe	Replace the fuel filter. In winter, place the car in a warm garage, blow out the fuel lines
The fuel pump does not create the required pressure in the system	Check the pressure in the fuel rail, make sure the mesh filter of the fuel module is clean	Clean the fuel module mesh filter. Replace faulty fuel pump and pressure regulator
The injectors or their power supply circuits are faulty	Check the injector windings and electrical circuits with an ohmmeter (no breaks or short circuits)	Replace faulty injectors, ensure contact in electrical circuits
Suction of extraneous air into the intake tract	Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. During the start-up, turn off the brake booster and plug the intake manifold fitting	Replace torn gaskets, parts with deformed flanges, faulty vacuum booster

Engine runs rough or stalls at idle

List of possible faults	Diagnostics	Methods of elimination
Unreliable connection of electrical circuits of engine control and power supply systems	Check the connection of the electrical connectors of the wire harnesses, the reliability of the contacts in the terminal blocks of the wires	Fix the faulty connections in the connectors
The gap between the spark plug electrodes is not within the norm	The gap of 0.7-0.8 mm is checked with a round feeler gauge	Set the correct gap or replace the spark plugs
Lots of carbon deposits on spark plug electrodes; carbon particles getting into the gap between the electrodes	Inspection	Check and replace spark plugs if necessary
Spark plugs are faulty: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact in the central electrode	The absence of external damage and sparking between the electrodes on the removed spark plug does not allow us to conclude that it is in working order	Replace the spark plugs
Damage to insulation of high-voltage devices and circuits	Use an ohmmeter to check for a break or "breakdown" (short circuit to ground) in the ignition coil winding and high-voltage wires	Replace damaged ignition coil and high-tension wires
The valve timing is out of order	Check the alignment of the marks on the crankshaft and camshaft pulleys	Set the correct relative position of the shafts. Check the compression
Low compression in engine cylinders (less than 11 bar): wear or damage to valves, their guide bushings and seats, sticking or breakage of piston rings	Check the compression	Replace faulty parts
Throttle position sensor is faulty	Check the throttle position sensor	Replace the faulty sensor
The idle speed control valve or its circuits are faulty	Replace the regulator with a known good one	Replace the faulty regulator
Suction of extraneous air into the intake tract	Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. During the start-up, turn off the brake booster by plugging the intake manifold fitting	Replace torn gaskets, parts with deformed flanges, faulty vacuum booster
The fuel pressure regulator is faulty	Check the fuel system pressure with a pressure gauge (2.8-3.3 bar)	Replace the faulty regulator
The adsorber is faulty, the connections of the fuel vapor recovery system tubes are not tight	Check the adsorber for damage, the serviceability of the purge solenoid valve and the tightness of their connections	Replace faulty canister, purge valve and tubes. Eliminate leaky connections
The throttle valve or its drive is stuck. Under these conditions, the ECU does not regulate the engine's idle speed	Check the ease of movement of the damper	Adjust the drive, throttle position. Replace the throttle assembly
The injectors are faulty (open circuit, short circuit of windings, contaminated atomizers)	Check the operation of the injectors	Replace faulty injectors. Clean dirty injectors
Camshaft cam wear	Inspection after partial disassembly of the engine	Replace the camshaft
The hydraulic compensators in the valve drive are faulty	Check the compression	Replace faulty hydraulic lifters
The vehicle speed sensor is faulty	After the car stops, the engine runs unevenly, but soon the idle speed stabilizes	Replace the vehicle speed sensor

The engine does not develop full power, the car does not have sufficient throttle response. Jerks and dips when driving the car

List of possible faults	Diagnostics	Methods of elimination
The air filter element is clogged	Check the condition of the air filter element	Blow out or replace the air filter element
Increased resistance to gas movement in the exhaust system	Inspect the exhaust system for dented or damaged pipes, check the condition of the catalytic converter	Replace damaged exhaust system components
Suction of extraneous air into the intake tract	Inspect the joints, check the fit of the hoses, fittings, and the tightening of the clamps. Disconnect the brake booster for a short time by plugging the intake manifold fitting. (Caution! The force on the brake pedal will increase significantly!)	Replace gaskets, parts with deformed flanges, faulty vacuum booster
Incomplete throttle opening	Determined visually with the engine stopped	Adjust the throttle actuator
The valve timing is out of order	Check the alignment of the marks on the crankshaft and camshaft pulleys	Set the correct relative position of the shafts. Check the compression
Low compression in engine cylinders (less than 11 bar): wear or damage to valves, their guide bushings and seats, sticking or breakage of piston rings	Check the compression	Replace faulty parts
The gaps between the spark plug electrodes do not comply with the norm	Check the gaps	By bending the side electrode, set the required gap or replace the spark plugs
Heavy carbon deposits on spark plug electrodes; carbon particles getting into the gap between the electrodes	Inspection	Check and replace spark plugs if necessary
Damage to insulation of high-voltage devices and circuits	Use an ohmmeter to check for a break or "breakdown" (short circuit to ground) in the ignition coil winding and high-voltage wires	Replace damaged ignition coil and high-tension wires
There is not enough fuel in the tank	By the level indicator and fuel reserve indicator	Add fuel
The fuel filter is clogged, water that got into the fuel system has frozen, and the fuel lines are deformed	Check the fuel system pressure (2.83.3 bar)	Replace the fuel filter. In winter, place the car in a warm garage, blow out the fuel lines. Replace defective hoses and tubes
The fuel pump does not create the required pressure in the system	Check the fuel rail pressure (2.83.3 bar), make sure the fuel module mesh filter is clean	Clean the fuel module mesh filter. Replace faulty fuel pump and pressure regulator
Poor contact in the fuel pump power supply circuit (including the ground wire) or its relay is faulty	Checked with an ohmmeter	Clean the contacts, crimp the wire tips, replace the faulty relay, wires
The injectors or their circuits are faulty	The CHECK indicator is on. Check the injector windings and their circuits with an ohmmeter (no breaks or short circuits)	Replace faulty injectors, ensure contact in electrical circuits
Generator faulty	Check the generator output voltage	Replace voltage regulator, repair or replace alternator
The exhaust gas recirculation valve is faulty	Check the operation of the valve	Replace the recirculation valve
The absolute air pressure sensor or its circuits are faulty	Check the sensitivity of the absolute air pressure sensor	Restore contact in electrical circuits, replace faulty sensor
One or both oxygen concentration sensors or their circuits are faulty	The CHECK indicator is on. You can evaluate the performance of the oxygen concentration sensors and the reliability of their electrical circuit connections using diagnostic equipment	Restore damaged electrical circuits. Replace faulty sensor
The ECU or its circuits are faulty	The CHECK indicator may be on. To check the ECU, replace it with a known good one	Replace the faulty ECU
The hydraulic compensators in the valve drive are faulty	Check the compression	Replace faulty hydraulic lifters
Severe wear of camshaft lobes	Inspection after partial disassembly of the engine	Replace a worn camshaft
Settling or breakage of valve springs	Inspection during engine disassembly	Repair the engine
The throttle position sensor or its circuits are faulty	The CHECK indicator is on. Check the throttle position sensor	Restore contact in electrical circuits, replace faulty sensor
Coolant temperature sensor or air temperature sensor or their circuits are faulty	Check the resistance of the sensor at different temperatures with a tester	Restore contact in electrical circuits, replace faulty sensor

Popping noises in the intake manifold

List of possible faults	Diagnostics	Methods of elimination
The hydraulic compensators in the valve drive are faulty	Check the compression	Replace faulty hydraulic lifters
Inlet valves stick in the guide bushings: resinous deposits on the surface of the valve stem or bushing, sediment or breakage of valve springs	Inspection during engine disassembly	Repair the engine
The valve timing is out of order	Check the alignment of the marks on the crankshaft and camshaft pulleys	Establish the correct relative position of the crankshaft and camshaft. Check the compression

Shots in the silencer

List of possible faults	Diagnostics	Methods of elimination
The hydraulic compensators in the valve drive are faulty	Check the compression	Replace faulty hydraulic lifters
Exhaust valves stick in the bushings: increased wear of the valve stem or bushing, sediment or breakage of valve springs	Inspection during engine disassembly	Repair the engine
The valve timing is out of order	Check the alignment of the marks on the crankshaft and camshaft pulleys	Set the correct relative position of the shafts. Check the compression
Spark plugs are faulty: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact of the central electrode	The spark plugs are tested on a special stand. The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to draw a conclusion about its functionality	Replace the spark plugs
Damage to the insulation of high-voltage devices and circuits - interruptions in spark formation	Use an ohmmeter to check for a break or "breakdown" (short circuit to ground) in the ignition coil winding and high-voltage wires	Replace faulty ignition coil and high-tension wires
The air filter element is clogged	Check the condition of the air filter element	Blow out or replace the air filter element

Increased fuel consumption

List of possible faults	Diagnostics	Methods of elimination
Leakage in the power supply system	Smell of gasoline, fuel leaks	Tighten the fuel line connections. Check the fit of the fittings; if the fit becomes loose, replace the corresponding components
Spark plugs are faulty: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact of the central electrode	The spark plugs are tested on a special stand. The absence of external damage and sparking between the electrodes on the removed spark plug do not allow us to draw a conclusion about its functionality	Replace the spark plugs
Throttle actuator malfunction	Check the gas pedal travel, the clearance in the drive (free pedal travel), make sure that the cable and pedal are not jammed	Replace faulty parts, lubricate the cable with engine oil
The idle speed control valve or its circuits are faulty	Replace the regulator with a known good one	Replace the faulty regulator
The throttle valve does not close completely	When held up to the light, a gap is visible between the throttle valve and the walls of the throttle body	Replace the throttle assembly
Increased pressure in the fuel line due to a faulty pressure regulator	Check the fuel system pressure with a pressure gauge (2.8-3.3 bar)	Replace a faulty fuel pressure regulator
Leaky injectors	Check the injectors	Replace faulty injectors
Coolant temperature or air temperature sensors or their circuits are faulty	The CHECK indicator is on. Check the sensor resistance with an ohmmeter at different temperatures	Restore contact in electrical circuits, replace faulty sensor
One or both oxygen concentration sensors are faulty	The CHECK indicator is on. You can evaluate the performance of the oxygen concentration sensors and the reliability of their electrical circuit connections using diagnostic equipment	Restore damaged electrical circuits, replace faulty sensor
The ECU or its circuits are faulty	To check, replace the ECU with a known good one	Replace the faulty ECU, restore damaged electrical circuits
Low compression in engine cylinders (less than 11 bar): faulty hydraulic compensators in the valve drive, wear or damage to the valves, their guide bushings and seats, stuck or broken piston rings	Check the compression	Replace faulty parts
Faulty: throttle position sensor, absolute air pressure sensor or their circuits	The CHECK indicator is on. Check the sensors and their circuits	Restore contact in electrical circuits, replace faulty sensor(s)
Increased resistance to gas movement in the exhaust system	Inspect the exhaust system for dented or damaged pipes, and check the condition of the catalytic converter	Replace damaged exhaust system components

Increased oil consumption (more than 500 g per 1000 km)

List of possible faults	Diagnostics	Methods of elimination
Oil leak through: crankshaft and camshaft seals; oil pan gaskets, cylinder head gaskets, oil pump housing gaskets; low oil pressure sensor; oil filter sealing ring	Wash the engine, then after a short run inspect the possible leak areas	Tighten the fastening elements of the cylinder head, oil pump, oil pan, replace worn seals and gaskets, low oil pressure sensor
Wear, loss of elasticity of oil-deflecting caps (valve seals). Wear of valve stems, guide bushings	Inspection of parts	Replace worn parts
Wear, breakage or coking (loss of mobility) piston rings. Wear of pistons, cylinders	Inspection and measurement of parts after engine disassembly	Replace worn pistons and rings. Rebore and hone cylinders
Use of oil of inappropriate viscosity	—	Change the oil
The crankcase ventilation system is clogged	Inspection	Clean the ventilation system

Detonation

(high-pitched metallic knocks that usually occur when the engine is running under load, especially at low speeds, such as acceleration under tension, etc., and disappear when the load is reduced)

List of possible faults	Diagnostics	Methods of elimination
Unacceptably low octane number of gasoline	—	Fill your vehicle with fuel recommended by the manufacturer
Engine overheating	According to the coolant temperature gauge	Eliminate the cause of overheating (see below "Engine overheats")
Lots of carbon deposits in the combustion chamber, on the piston bottoms, and valve plates	Inspection after removing the cylinder head	Eliminate the cause of carbon deposits (see "Increased fuel consumption", "Increased oil consumption"). Use oils of the recommended viscosity and, if possible, with low ash content
Spark plugs with the wrong heat rating are used	—	Use spark plugs recommended by the manufacturer

Insufficient oil pressure (low oil pressure indicator is on)

List of possible faults	Diagnostics	Methods of elimination
Low oil in engine	According to the oil level indicator	Add oil
Use of oil of inappropriate viscosity	—	Change the oil
Clogged oil receiver mesh	Inspection	Clean the mesh
The oil filter is faulty	Replace the filter with a known good one	Replace the faulty oil filter
Misalignment, clogging of the oil pump pressure relief valve or weakening of the valve spring	Inspection	Clean the valve. Replace the faulty valve or pump
Wear of oil pump gears	Determined by measuring the parts after disassembling the oil pump	Replace the oil pump
Excessive clearance between bearing shells and crankshaft journals	Determined by measuring the parts after disassembling the engine	Replace worn bearings. Replace or repair crankshaft if necessary
Low oil pressure sensor is faulty	We unscrew the low oil pressure sensor from the hole in the oil pump housing and install a known good sensor instead. If the indicator goes out after starting, the unscrewed sensor is faulty	Replace the faulty low oil pressure sensor

The engine gets very hot (the pointer arrow is in the red sector of the scale)

List of possible faults	Diagnostics	Methods of elimination
Coolant temperature sensor or gauge is faulty	Check the indicator and sensor with a tester	Faulty sensor, indicator - replace
Thermostat is faulty	Check the thermostat for proper operation	Replace the faulty thermostat
Insufficient amount of coolant	The fluid level is below the "MIN" mark on the expansion tank	Fix leaks. Top up coolant
Lots of scale in the cooling system		Flush the cooling system with a descaler. Do not use hard water in the cooling system. Dilute concentrated antifreeze with distilled water only
The radiator cells are dirty	Inspection	Rinse the radiator with a jet of water under pressure
Coolant pump is faulty	Remove the pump and inspect the unit	Replace the pump assembly
The cooling system fan does not turn on	Check the fan circuits	Restore contact in electrical circuits. Faulty fuse, relay, electric motor, temperature sensor, ECU - replace
Unacceptably low octane number of gasoline	—	Fill your vehicle with fuel recommended by the manufacturer
Lots of carbon deposits in the combustion chamber, on the piston bottoms, and valve plates	Inspection after removing the engine cylinder head	Eliminate the cause of carbon deposits (see "Increased fuel consumption", "Increased oil consumption"). Use oil of the recommended viscosity and, if possible, with low ash content
Exhaust gas leak into the cooling system through a damaged cylinder head gasket	There is a smell of exhaust gases in the expansion tank and bubbles are floating up	Replace the cylinder head gasket. Check the cylinder head for flatness

The engine cooling fan is constantly running (even on a cold engine)

List of possible faults	Diagnostics	Methods of elimination
Open circuit in the coolant temperature sensor or its circuit	The CHECK indicator is on. The sensor and circuits are checked with an ohmmeter	Replace the faulty sensor
The fan relay contacts do not open	Checking with a tester	Replace the faulty relay
The ECU or its circuits are faulty	Check the ECU or replace it with a known good one	Replace the faulty ECU

The engine takes a long time to warm up to operating temperature

List of possible faults	Diagnostics	Methods of elimination
Thermostat is faulty	Check the thermostat for proper operation	Replace the faulty thermostat
Low air temperature (below -15°C)	—	Insulate the engine: install shields in front of the radiator, but do not cover more than half of its area

Coolant level in the expansion tank has dropped

List of possible faults	Diagnostics	Methods of elimination
Damage to radiators (engine and heater), expansion tank, hoses, loosening their fit on the pipes	Inspection. Tightness of radiators (engine and heater) tested in a water bath with compressed air under a pressure of 1 bar	Replace damaged parts
Coolant pump seal leaking fluid	Inspection	Replace the coolant pump
Damaged cylinder head gasket. Block or cylinder head defective	The oil level indicator shows a whitish emulsion. There may be copious white smoke from the muffler and oil stains on the surface of the coolant (in the expansion tank). Coolant leaks on the outer surface of the engine	Replace damaged parts. Do not use water in the cooling system, fill with coolant that meets the climatic conditions

Extraneous noises and knocks in the engine

List of possible faults	Diagnostics	Methods of elimination
The hydraulic compensators in the valve drive are faulty	Check the hydraulic lifters	Replace faulty hydraulic lifters
Settling or breakage of valve springs	Inspection during engine disassembly	Repair the engine
The timing belt is worn out. The timing belt tension roller is faulty	Inspection	Replace the belt. Replace the faulty timing pulley
Knocking of the crankshaft and camshaft, connecting rod and main bearings, pistons, piston pins, play or seizure in the bearings of the generator, coolant pump	Examination	Engine repair, coolant pump replacement, generator repair or replacement
One or more powertrain mounts have lost their elasticity or have been damaged	Inspection	Replace the powertrain mount
Low oil pressure (at minimum crankshaft speed at idle, the pressure in the lubrication system of a warm engine should be at least 0.5 bar)	Check the pressure in the lubrication system. You can measure the pressure by connecting a pressure gauge to the oil line, unscrewing the oil pressure sensor	Troubleshoot the lubrication system

Strong engine vibration

List of possible faults	Diagnostics	Methods of elimination
Uneven compression across cylinders over 2 bar: faulty hydraulic compensators in the valve drive, wear or damage to valves, seats; wear, sticking or breakage of piston rings	We check the compression. The compression should be at least 11 bar	Replace faulty parts
Damage to the insulation of high-voltage devices and circuits - interruptions in spark formation	Use an ohmmeter to check the ignition coil winding and high-voltage wires for breakage or "breakdown"	Replace faulty ignition coil and high-tension wires
Defective spark plugs	Check the spark plugs	Replace defective spark plugs
The gap between the spark plug electrodes is not within the norm	The gap of 0.7-0.8 mm is checked with a round feeler gauge	By bending the side electrode, set the required gap or replace the spark plugs
Heavy carbon deposits on spark plug electrodes; carbon particles getting into the gap between the electrodes	Inspection. The carbon deposits can usually be used to determine the spark plug's performance and the engine's condition	Clean the spark plugs with compressed air or mechanically (do not damage the insulator!). Identify and eliminate the cause of increased carbon formation in the combustion chamber, replace the spark plugs if necessary
Open or short circuit in the injector windings or their circuits	Check the injector windings and their circuits with an ohmmeter	Replace faulty injectors, ensure contact in electrical circuits
The injectors are leaky (overflow) or their sprayers are dirty	Check the tightness and spray pattern of the injectors	Contaminated injectors can be washed on a special stand. Replace leaky and heavily contaminated injectors
The power unit supports have lost their elasticity or have been damaged, or their fastening has become loose	Inspection	Replace the supports, tighten the fasteners

Increased content of harmful substances in exhaust gases

List of possible faults	Diagnostics	Methods of elimination
The injectors are leaky (overflow) or their sprayers are dirty	Check the tightness and spray pattern of the injectors	Contaminated injectors can be washed on a special stand. Replace leaky and heavily contaminated injectors
Damage to the insulation of high-voltage devices and circuits - interruptions in spark formation	To check the high-voltage wires and ignition coil, replace them with known good ones	Replace faulty ignition coil and high-tension wires
Defective spark plugs: current leakage through cracks in the insulator or carbon deposits on the thermal cone, poor contact of the central electrode	Check the spark plugs	Replace defective spark plugs
The phase sensor or its circuits are faulty	The CHECK indicator is on. Use a tester to check the phase sensor for proper operation	Restore contact in electrical circuits, replace faulty sensor
Coolant temperature sensor or air temperature sensor is faulty	Check the sensor resistance at different temperatures with an ohmmeter.	Replace the faulty sensor
The throttle position sensor or its circuits are faulty	The CHECK indicator is on. Check the throttle position sensor for proper operation	Restore contact in electrical circuits, replace faulty sensor
One or both oxygen concentration sensors are faulty	The CHECK indicator is on. You can evaluate the performance of the oxygen concentration sensors and the reliability of their electrical circuit connections using diagnostic equipment	Repair damaged electrical circuits. Replace faulty sensor(s)
The absolute air pressure sensor and its circuits are faulty	The CHECK indicator is on. Check the sensitivity of the absolute air pressure sensor	Restore contacts in electrical circuits. Replace faulty absolute air pressure sensor
The ECU or its circuits are faulty	To check, replace the ECU with a known good one	Restore contacts in electrical circuits. Replace faulty ECU
The catalytic converter of the exhaust gases is faulty	You can check the serviceability of the catalytic converter of exhaust gases using diagnostic equipment	Replace the catalytic converter
Increased pressure in the fuel rail due to a faulty pressure regulator	Checking the fuel rail pressure with a pressure gauge (2.8-3.3 bar)	Replace the faulty regulator
Increased air flow resistance in the intake tract	Check the air filter element, intake tract (absence of foreign objects, leaves, etc.)	Clean the intake tract, replace the dirty air filter element

Engine management system malfunction indicator light comes on when engine is running

List of possible faults	Diagnostics	Methods of elimination
The ECU, sensors, injectors or their circuits are faulty. The malfunction may be temporary, then the indicator may go out itself, without any intervention	See previous topics "Troubleshooting". Full diagnostics of the control system is carried out using specialized equipment	When most sensors fail (except crankshaft position sensor) you can drive to the repair site on your own. Replace faulty ECUs, sensors, injectors, wires
Disconnected (perhaps for verification) individual sensors, injectors, after which the ignition was turned on (started the engine). In this case, a corresponding fault code is recorded in the computer memory, which is not erased even after the electrical connections are restored	—	Remove the negative terminal from the battery terminal for at least 10 seconds. This will erase all fault codes from the ECU memory

The article was borrowed from the website: chevyman.ru