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P0420 What could it be?
Posted: Sun Feb 18, 2007 4:24 pm
by jdmvtec93
Says
P0420 Catalyst System Efficiency Below Threshold
What could be the problem that causes this code?
Posted: Sun Feb 18, 2007 5:48 pm
by rensoyka
1. If you are running a race header, the sensor is telling you that your cat is missing. Install a defouler.
2. If you still have a cat, it's toast.
3. Your secondary O2 sensor may be malfunctioning.
Posted: Mon Feb 19, 2007 4:41 am
by jdmvtec93
ok i am runing a Jackson Racing race header.
do i have to disable the obd11 option?
Posted: Mon Feb 19, 2007 5:22 am
by rensoyka
That's one option, some people choose that one, others use the defouler method. Disabling OBDII will turn off the CEL.