Codes PO133 & PO420

[fordman3557456]

Has anyone else had both of these codes go off at once and what is the likely culprit? Car is running and driving fine, just had it checked because I was tired of seeing the check engine light staying on.

 

[swetrid]

Replace the o2 sensor and see if cat code comes back. Slow response of o2 sensor can cause false cat codes.

 

[fordman3557456]

Which one?

 

[bobflood]

Which one?

P0133 is bank 1, sensor 1. Bank one is the pass side of engine; sensor 1 is the first one, ahead of the cat. I agree with swetrid - replace the O2 and see if cat code comes back. This particluar cat code has been appearing once or twice a year on mine for years. I just turn it off.

 

[fordman3557456]

How can I get at the correct o2 sensor? My car is a 98 5.0 AWD.

I found this link http://www.explorerforum.com/forums/showthread.php?t=209770, is this the correct process? Is there a better detailed guide anywhere? Thanks

 

[bobflood]

How can I get at the correct o2 sensor? My car is a 98 5.0 AWD.

I found this link http://www.explorerforum.com/forums/showthread.php?t=209770, is this the correct process? Is there a better detailed guide anywhere? Thanks

This access is used to unplug/plug the sensor wires out of/into the wiring harness. I have never had to do this surgery to replace the O2 sensors in my 2WD Explorer. All four plugs are on top of the transmission, but I have always been able to get to them by reaching up around the transmission. In an AWD version, the transfer case might be in the way - I don't know. The sensor itself is in the header pipe on the pass side before the cat.