my roommate has 01 pathfinder and his check engine light keeps coming on. and instead of takin it to the dealer i told him to take it to autozone to see if it was somethin stupid and simple i could just fix for him. they gave him a truoble code : p0420-“the pcm has determined that the catalyst system eff. for bank 1 is below threshold for the current engineoperating conditions”. funny thing is they told him there might be “oil” getting into the convertor. can anyone interject or point me in the right direction if this is a simple fix… if not im sending him right to hybrid.
i would check 02 sensors first…they cause all kinds of wierd codes…and a common problem on Nissans
Sounds like a bad cat.
If there are 2 O2 sensors try switching them to see if the problem moves to the other side.
X…
that was my thought…
the cat would only go bad if its dumping raw gas or oil down the manifolds…does it have an oil consumption problem…does it still have a warranty??
not sure, but i dout it 2001 w/94k on it. just goin by what the tarts at autozone are telling him. the reason i thought it might be a prob with the cat. is because around that mileage my cat. was internally in peices in my mazda.
if the cat shit the bed wouldnt the truck sound significantly different? i would assume so - maybe not - but that makes me think o2
also dont trust the tarts at the zone they are dumb…there are only two i trust and its only because i ahve been friends with one for most of my life and he is a highly experienced mechanic…doest he truck smell funny in any way…is it running like shit…
i would still try messing with 02s
ill try that 1st, thanks
+1 for bad 02 sensor…
convertor is not doing its job, you need a new convertor, the fedaeral warranty is 8yrs/80k, so your past that, just go to a trustworthy muffler shop and get the cat repalaced