Code P0420 Help!
05-06-2010, 05:30 PM
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Code P0420 Help! I have code P0420 present. Car has flowtech long tubes, with a custom y pipe, and flowmaster cat back. Also has high flow cats in the custom y pipe. Entire exhaust system only has 2,000 miles on it. I recently had the code before, and replaced both upstream 02 sensors, which fixed it that time. Then, I got the code again, which was caused by a exhaust leak(Blown out header gasket). After replacing the header gasket, 500 miles later, it is on again. I brought it to an exhaust shop, and they recommended a tune, to compensate for the headers and high flow cats. They said that the computer said that the 02 sensor parameters are beyond limits. Any suggestions? By the way, the car only has 55,000 miles on it, if that makes a difference at all.
Last edited by 98blueSS420; 05-06-2010 at 05:40 PM. Reason: Forgot to add mileage.
05-07-2010, 02:48 AM
#4
I would get this code from time to time after my LT/Catted-Y install.
I believe this code is caused by the cats of an aftermarket Y-pipe not being as efficient as the factory cats. So the downstream O2's pickup on this and throw the PO420 (Catalyst Insufficient Performance) Code.
I now have a Mail-Order-Tune, so my rear O2 Sensors are shut off. Thus eliminating the chance for this to pop up again.
Although, you wouldn't have to get an Aftermarket Tune for this reason alone. Any codes having to do with the Rear O2 Sensors won't put the PCM into Open Loop, so there's no performance loss when the SES light comes on for this reason.
I believe this code is caused by the cats of an aftermarket Y-pipe not being as efficient as the factory cats. So the downstream O2's pickup on this and throw the PO420 (Catalyst Insufficient Performance) Code.
I now have a Mail-Order-Tune, so my rear O2 Sensors are shut off. Thus eliminating the chance for this to pop up again.
Although, you wouldn't have to get an Aftermarket Tune for this reason alone. Any codes having to do with the Rear O2 Sensors won't put the PCM into Open Loop, so there's no performance loss when the SES light comes on for this reason.
05-08-2010, 01:08 PM
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How to tune out rear o2's How do I tune out the rear o2 sensors? Is this something that can be done with a handheld programmer/tuner? By the way, thanks for all of the usefull info, everyone! This is why I love this website !
