Question about 1998 Chevrolet Cavalier
I keep getting a 0420 code. The entire exhaust, to include the cat and both 02 sensors have been replaced. I cannot find any advanced troubleshooting procedures for this code. Anyone have any ideas?
Here is something from a reference guide that we follow at my shop, hope it helps.
When diagnosing a PCM code PO420, be sure to determine the cause of the converter failure. Converters are not likely to fail without an external cause. Typical causes are: fuel pressure regulator leak, engine misfire, dirty fuel injectors, coolant consumption, etc. Also, be aware that some converters on the market will cause this code or codes due to a lack of oxygen storage capacity. A component that must be in these converters, Cerium, is required to store, then slowly release oxygen.
Posted on Mar 10, 2009
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Posted on Jan 02, 2017
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Catalyst System Low Efficiency
Air leaks at the exhaust manifold or in the exhaust pipesBase engine problems (i.e., high engine oil or coolant usage)Catalytic converter is damaged, contaminated or has failedContinuous engine misfire conditions, or weak or low coil outputFront HO2S or rear HO2S is contaminated with fuel or moistureRear HO2S is loose in the mounting hole (check it for a leak)Front HO2S older (aged) than the rear HO2S (HO2S-12 is lazy)
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