problem check engine.....

[tvalentino]

so i went off roadin in mud and 2ft water with my friends and got a check engine light on my way home.... used a OBDII and got a P0420 code "running lean" says catalyst efficiency low-bank 1... so i was thinking it might be the o2 sensor, a spark plug, vacuum leak, or the cat but i doubt the cat... any other tips on what to check or possibilities what it might be?

 

[btexpress]

P0420 is NOT telling you a sensor is at fault. If the sensor was faulty it couldn't set this particular code. Generally P0420 is a weak or failing, or inop cat converter. Could you have gotten water into it while having so much fun? Give it a chance to dry out and test again.

Another possibility is mud caked around the outside of the sensor, effectively blocking the air venting of the sensor, thus causing erroneous readings which could have set the code.

 

[btexpress]

On a 1996 Explorer, the mileage just may be enough for the cat to have outlived itself. Check for mud on the sensor AFTER the cat then decide course of action.

 

[tvalentino]

so now after driving it for a few days it turned off while i was driving and did not come back on yet.... hmm wierd

 

[btexpress]

so now after driving it for a few days it turned off while i was driving and did not come back on yet.... hmm wierd

Having cleared the codes, (you did, right?) it will take a while for this type of code to reappear if there is actually a problem. The monitor for the cat takes either exact driving situation or a long time for the monitor to run.

Not to worry.

 

[tvalentino]

well i cleared it when i used the OBDII.... then it came back up in 2 days but like i said when it was on a couple of days ago i was driving and it turned off by itself while i was on the highway.... i didnt clear it this time.... it turned off by itself...

 

[ThePhoenix]

i thought they didnt clear themselves. you might have a bad something or other....light or omputer...

 

[tvalentino]

yea not too sure what it is..... well i think i will just change the cat anyways its a 96 so thats 12yrs old plus i have to smog my car by jan 29 so it will help with that too...