First time poster. I have a 2000 626 with about 64K miles, a 2.0 and auto trans. I have been working the P0420 problem with mine. I have changed out both the front and rear O2 sensors. Did the rear first. After about 3 weeks the light came back. Did the front, then light came back after 2 months. In the reading I have done, I have seen mentioned that the cat could be bad. I have also seen there is a TSB regarding the limits the PCM senses the tolerence level between the front and rear O2 sensor. This tolerence window is set too close together and sometimes sets off the code. You can take the car into the dealer and they expand the tolerence window within the PCM. I'm not sure if the TSB was for this year 626.
Does anyone have any other ideas for things to check?
have the same problem?
Saturday, April 7th, 2007 AT 9:32 PM