Mike
- posted
19 years ago
Mike
A PO420 doesn't indicate a failed O2 sensor(s), it signifies a loss of bank one catalyst efficiency which, being plugged makes perfect sense. Plugged cats are caused by miss-fires, over fueling, under fueling, cam timing problems, vacuum leaks, that sort of stuff.
thanx, I had other codes telling of bad 02 sensors before but the 0420 was always there. Once I had a multiple misfire code. Once had bad heater for 02 sensor etc. Can a plugged cat take out 02 sensors? I'm just trying to get to the root cause here. The engine has 133k on it. What's the next thing to start looking at?
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