A while back I had a P0420 code pop up on my '06 Liberty. I replaced the downstream O2 sensors, cleared the code, and a short while later the CEL comes on again. Check the codes again, and this time I get a P0004 code. Clear it, drive to work the next day, and the CEL comes on with a P2200 code. Try again and on the way home get a P2204 code. Next day back to a P0420 code. They seem to be coming up randomly, although never more than one code at a time. I'm using a ScanGauge II to read and clear the code. My original assumption was that the driver's side cat has gone bad due to a a bit of off-road clearancing, but the variety of codes that've come up has me questioning what the real problem is. Any thoughts, or has anyone experienced a similar problem?

P0004 = Fuel volume regulator control circuit high
P2200 = NOx sensor circuit bank 1

Sounds like a bad fuel regulator,or crimped fule line.And of course since you damaged the cat that would need to be replaced as well.

i would deff check all your lines underneath to see if any damage was done. and if you replace your cat, might as well go with a high flow

here some choices --- http://www.quadratec.com/category/Jeep+ ... /index.htm

Thanks for the replies. The last code P2204 is "NOx Sensor Circuit Intermittent Input" - unfortunately that doesn't help clear things up any further since I haven't a clue about the NOx sensor! NAPA has catalytic converter assemblies pre-welded with pipes, flanges, and O2 sensor taps. I think this should do the trick for the driver's side:

http://www.napaonline.com/masterpages/N ... Direct+Fit

I'll see about testing the fuel regulator too - that looks like a real blast to get to. Still it seems weird that if there's multiple problems, which the codes would lead me to believe, I'm only getting one code at a time - especially considering how quickly the CEL turns on.

Just a quick sanity check before I order - anyone have experience with the NAPA direct fit cats or other replacement options? The only things I've seen discussed are replacing using the $spendy$ OEM system, or replacing the entire exhaust system and using a high flow cat (been there, zero interest in doing it). If the system I linked to at NAPA is truly a bolt-on replacement for $284 I'm surprised other folks haven't been all over this!