Caution: Do not reinstall the exhaust manifold gasket. An improperly installed or poorly sealing gasket may affect the operation of the OBD II diagnostic system.
1. Flush the exhaust manifold and heat shield with solvent.
2. Dry the exhaust manifold with compressed air.
3. Check the condition of the manifold sealing surface.
4. Check the condition and reliability of the heat shield.
5. Check the condition of the threads of the exhaust system inlet pipe mounting studs.
6. Using a measuring prism and a flat feeler gauge, check the exhaust manifold flange for warpage.
Warpage along the two front or two rear flanges should be no more than 0.25 mm and no more than 0.5 mm along the entire length of the manifold.