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View Full Version : Troubleshoote code P0420

98Cobretti
11-13-2002, 08:38 PM
I got this code and it came up as: The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current engine operating conditions. (bank1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank).

After I got the code, I bought the Mil eliminators and thought that it was fixed, but I just got a check engine light again the other day, and havent had it scanned yet, but am pretty sure it is the same thing. So is this a malfunctioning catalytic converter, or a malfunctioning O2 sensor? Help!
cobragb
11-13-2002, 10:43 PM
That's strange. I would say that something is up with the mil eliminator on the passenger side. You may want to recheck your wiring.

Glen
98Cobretti
11-14-2002, 03:54 AM
I bought the Dallas plug in kind, I don't think its wiring. I just wonder if it could be a bad cat or something, my car makes a funny smell, not really strong but almost smells like a bad cat, rotten egg smell a little. The x pipe has only been on for about 6000 miles or so maybe a little more.
cobragb
11-14-2002, 11:10 PM
It doesn't matter if you have bad cats or not with mil eliminators, the computer should ignore the back O2 sensors. Are you sure that is the only code you are pulling? I would try to switch the sensors, then the eliminators one at a time and see if the problem moves to the other bank.

Good luck,
Glen
98Cobretti
11-19-2002, 05:21 AM
I would have it scanned, but the check engine light went away, I will switch the 02 sensors, and if it comes up again I am going to go get it scanned again and see what comes up. What if it isnt the rear sensors at all, but the front going bad maybe?
cobragb
11-20-2002, 10:03 PM
Originally posted by 98Cobretti
What if it isnt the rear sensors at all, but the front going bad maybe?

I am pretty sure it would be a different code for the front sensors.
98Cobretti
11-20-2002, 10:23 PM
How do you know what sensor it is, it only says bank 1, it doesnt say front or rear sensor, is there a way to tell what exactly that code means? I just have the info the scanner said. Is that a code distinctly for the rear sensors? Thanks for the help by the way!