2005 Chrysler Pacifica Eng Mal Code 0420

BOBHEINRICH

MEMBER
2005 CHRYSLER PACIFICA
6 CYL
FWD
AUTOMATIC
81,000 MILES

Just recently the engine light came on. It registered code 0420, stating that the right bank o2 limits are incorrect. What is the usual cause of this? Several mechanics have said that replacing the o2 sensors will not correct it and doubt it is the catalyic converter. What is the MOST LIKELY cause? I know you can troubleshoot from a desk, but in your experience, what is really the problem? The engine uses about 1 qt of oil every 1500-2000 miles. Been doing that since I bought it with 20,000 miles on it.

Also, what is the interval for replacing the timing belt? There is no mention of it in the owners manual and the maintenance guide only goes up to 100,000 miles.

Thanks,

Bob

1 Reply

SERVICE WRITER

MECHANIC
9,123 POSTS

Ouch Bob.

Catalytic converters are a common cause of that code. The warranty is 8 years/ 80,000 miles.

Having said that, I believe the oil burning is coating the prescious metals of the converter and causing a lack of a chemical reaction to reduce pollutants.

I believe if your replaced the converter it will be a temporary fix until the oil burning is brought under control. You can test mey theory by pulling the plugs and looking for signs of burning oil

This "should" clean off the layer that is insulating the precsiuos metals from doing thier job.
IF that works, get the oil burning problem fixed.