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View Full Version : CEL Running too rich, nearly stock..


Metallic36
08-25-2008, 12:49 AM
Wondering what would cause this.. didn't happen until I got my stock exhaust put back on. Had a 2.5" catless exhaust before. Wondering the chances of it being the O2 sensor, or if it would go away if I moved the 2nd O2 sensor to the j-pipe? Basically stock again, but the CEL didn't come on until after stock exhaust was put on. Had a shop do it, so I don't know if they possibly messed up the O2 sensor.
25FConv
08-25-2008, 01:18 AM
its probably been done but did they reset the ECU? so it can relearn?
Metallic36
08-25-2008, 01:58 AM
Yeah, I've done this a few times. It wasn't done automatically after the other exhaust was put on, but once I got home I did it. It drove fine for a while, then the cel came on, I cleared it off, reset the ecu.. I made some changes with vacuum lines, etc then drove it for a couple days straight on a few minor road trips, then the cel has come back on again after about two weeks of it not being on.


its probably been done but did they reset the ECU? so it can relearn?
25FConv
08-25-2008, 09:03 AM
Did you find out what the code was for the CEL? Maybe the an oxygen sensor just needs to be cleaned or something.
cmahlig
08-25-2008, 09:39 AM
sensor is dirty or damaged
Metallic36
08-25-2008, 09:40 AM
The code I got was P0172 Fuel Trim too Rich (Bank 1)

Now that I looked that up and it says Bank 1, is that meaning the 1st O2 sensor? Odd that it's that one..
Jspeed17
08-25-2008, 10:02 AM
Well i can tell you the 2nd o2 sensor only monitors the cats, so moving it will do nothing unless you want another code for catalyst efficiency :), i really don't see how changing an exhaust can make the engine run rich....pull out your first o2 sensor in the manifold see if its damaged, mine once-looked like it had melted quite a bit!!!! Also make sure you have your vacuum hoses correct especially to fuel press. reg.
Metallic36
08-25-2008, 10:15 AM
Thanks, I'll check on those things. Hopefully I'll find out what's going on.


Well i can tell you the 2nd o2 sensor only monitors the cats, so moving it will do nothing unless you want another code for catalyst efficiency :), i really don't see how changing an exhaust can make the engine run rich....pull out your first o2 sensor in the manifold see if its damaged, mine once-looked like it had melted quite a bit!!!! Also make sure you have your vacuum hoses correct especially to fuel press. reg.