Check Engine light stays on
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Elder User
Joined: Mar 2004
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Check Engine light stays on
I got my truck from my dad not too long ago and he had the cat reemed out and put a different muffler on it (I am not sure of the brand). The check engine light comes on and stays on when the codes are read and cleared. It refers to the cat (I can't remember the actual code, it is on the bill at home) and it comes on since the cat has been reemed out. I have a spare 3" exhaust with a flowmaster muffler on it that I am going ot put on this truck at some point and not have the cat. I can get an adapter from Flowmaster that puts the 2 exhaust pipes from the manifolds into one 3" outlet, and the guys from the shop say that they can incorporate the O2 sensor into it.
My question is is there a way that I can keep the check engine light from comming on right now, and secondly, will it stay on or will I be doing any harm when I replace the exhaust system with no cat? Can I have it reprogramed so that the light does not come on if there is no cat at all?
Thanks for the help.
My question is is there a way that I can keep the check engine light from comming on right now, and secondly, will it stay on or will I be doing any harm when I replace the exhaust system with no cat? Can I have it reprogramed so that the light does not come on if there is no cat at all?
Thanks for the help.
Postmaster
Joined: May 2002
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From: Broken Arrow, OK
Yes, the light is because the cat is gone. There is an O2 sensor downstream of the catalyst. When that sensor starts reading the same as the upstream O2 sensor it tells the computer that the catalyst is no longer working efficiently. The only way to truly repair the problem is to replace the cat. There are many bandaid fixes, including installing a simulator in the downstream O2 sensor wiring. I would just replace the catalyst with an aftermarket part. A good cat won't hurt performance any.
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Elder User
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Thanks for explaining how this works. I did not know that there were two O2 sensors. So can I replace this system with the other exhaust and just have 1 O2 sensor, or will I really goof up the computer?
Posting Guru
Joined: Sep 2004
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Originally Posted by bchunter
So I guess my best bet would be to get a good cat then put the exhaust system that I have from the cat back.
Sounds like a plan, good luck
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Junior User
Joined: Jan 2004
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From: Seattle, WA
Originally Posted by bchunter
and the guys from the shop say that they can incorporate the O2 sensor into it.
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Postmaster
Joined: May 2002
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From: Broken Arrow, OK
Originally Posted by Silver Streak
There is an O2 sensor downstream of the catalyst. When that sensor starts reading the same as the upstream O2 sensor it tells the computer that the catalyst is no longer working efficiently.
That's why.