Contour Enthusiasts Group Archives Forums General Troubleshooting Got Po420

got my CEL checked, bank 1 cat not good... so which CAT is this? iam running without the main CAT, and have a filter with custom exhaust, i read a post about this earlier and geo somebody had info like, damaged mainfold, damaged exhaust pipes etc... anything special i should look for? if the lower ypipe was damaged or me having a custom exhuast cause this??? it also says something about misfire, wouldnt a misfire appear on the CEL check??? PO420 was only code to appear.. i have 64k, any advice would be aprreciated, thanks..


Diagnostic Trouble Codes (DTC) P0420 and P0421 indicate that bank 1 catalyst system efficiency is below the acceptable threshold.

Diagnostic Trouble Codes (DTC) P0430 and P0431 indicate that bank 2 catalyst system efficiency is below the acceptable threshold.

NOTE 1: Complete the spark timing check in «Quick Test» before proceeding with this test step. Spark timing retarded below specification may increase exhaust gas temperature and decrease catalyst efficiency over time.

NOTE 2: Be sure customer has not:
(1) Refueled vehicle with leaded gasoline.
(2) Experienced high vehicle oil consumption.

NOTE 3: If entering this Pinpoint Test for symptoms only, go immediately to HF5: CHECK REAR HO2S WIRING.

NOTE 4: Internal deterioration of a catalytic converter is usually caused by abnormal engine operation upstream of the catalyst. Events that may produce higher than normal temperatures in the catalyst are particularly suspect. For example, misfiring can cause higher than normal catalyst operating temperatures.

Possible causes:
-- Use of leaded fuel.
-- Oil contamination.
-- Cylinder misfiring.
-- Damaged HO2S.
-- Damaged ECT sensor.
-- Downstream HO2S wires improperly connected.
-- Fuel pressure too high.
-- Damaged exhaust system pipe.
-- Damaged exhaust manifold.
-- Damaged muffler/tail-pipe assembly.
-- Damaged catalytic converter.

.?

You might want to try a new bank 1 (firewall side) downstream (I think, could use some help here) oxygen sensor. I'm making the assumption you have a duratec. If that doesn't work, you are still under the 80,000mi emissions warranty to get that pre-cat replaced. Don't know how your aftermarket stuff might affect the warranty though. Also, if the custom exhaust is new and this is the first time this has popped up, you should consider checking for damage to the rear exhaust manifold and pre-cat.