Code PO420

[jeepnutz]

I just took an OBD 2 reading on my 2002 explorer and it came up with the "PO420" code which indicates a bad catalytic converter. Could this be the same reason the car idles so high? Does anyone know a quick fix for this? or do I need to replace the converter.

Thanks for any advise

 

[matt0248]

a P0420 should not cause a high idle. It is possible that the oxygen sensors are going bad and can set this code. But, it usually means that the converter has worn out and lost it ability to do it's job.

 

[jeepnutz]

Thanks for the feedback.... where is the oxygen sensors, are they easy to replace - I'm hoping that they are cheaper then buying a CC. I've also replaced the "Throttle Position Sensor" and the "Idle Air Control" valve in hopes that I could get my idle back down, but had no luck.

 

[matt0248]

There are 4 oxygen sensors. Two before the cats, one on each bank of the engine. And two after the first two cats, one for each bank. They can be difficult to access and remove. There are special wrenched and sockets to help get them out, and because they can be rusted in place sometimes a little heat is necessary to free them up.

If you still have a high idle check for vacuum leaks, broken vacuum hoses and such. Do you have the v6? If so they are known to have intake manifold gaskets leak and will cause idle problems.

 

[jeepnutz]

Don't think I'll be messing with the oxygen sensors after that being said. How ever I did look for vaccum leaks for the high idle and couldn't find any. When the car is first started the rpm's run about 1500 and stay there until I drop it in gear then the rpm's drop to about 800. It dosen't matter how far or how long I drive it - the second I put it in Park the rpm's climb back up to 1500..... any ideas?

 

[matt0248]

Could be a bad idle air control valve, dirty or binding throttle body, not closing all the way. Try disconnecting the IAC and see if it stalls.

 

[jeepnutz]

Finally got some time today to check out my idle problem. When I pulled the electric snap plug thingy off the IAC, the car did stall. I wasn't sure if that was what was suppose to happen or not, so I replaced the IAC and it still idles at 1500 rpm until I drop it in gear. I also replaced the TPS but that dosent make a difference either. I'm confused.... is there something else I can try?
Thanks for all the feedback matt0248.