Mechanics

CATALYTIC CONVERTOR CODES WILL NOT C

1997 Oldsmobile Aurora

Computer problem
1997 Oldsmobile Aurora V8 Front Wheel Drive Automatic 135000 miles

convertor replaced at 110,000 and o2 sensors, code cleared for 150 miles and returned. Replaced convertor and used different sensors, code does not clear. Car runs great but the light is annoying.
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Dpn1460
October 4, 2010.



What code are you getting?

P420, any help will be appreciated.

Tiny
Dpn1460
Oct 28, 2010.
A PO420 is a generic fault code indicating a drop in converter efficiency. I realize you replaced the converter and O2 sensors. Did you check to make sure the sensors are switching between a rich.08 and a lean.03 voltage shortly after starting the vehicle. If there is no change (flat line) you have a bad sensor. Most times a bad sensor will set a sensor code and not the converter. However, I have seen situation where the sensors are good enough to prevent the 02 code but bad enough to set a PO420. Also, is the converter new? Were the sensors you used new? Is the converter OBD2 complient?

Let me know