OBD II question

[jaybee]

Is it possible for an exhaust leak near the downstream O2 sensor to cause a check engine leak by causing an unstable or unexpected signal?

[tomslik]

Is it possible for an exhaust leak near the downstream O2 sensor to cause a check engine leak by causing an unstable or unexpected signal?

yes, it's possible.
but if it's a small leak, not real likely.
gonna need it scanned, even if just to get the light off.

[wayne petty]

yes....


the downstream oxygen sensors look at the output of the cat....


looking for a nice clean  but hot breeze blowing past...   if it sees too much oxygen or too little...   it is going to alert the system and set a code...


they call these the catalyst monitors...

[jaybee]

Thanks, that's what I expected.

[teal32]

I guess that puts a stop to my idea of installing a couple of cut-outs on the '40 Chevy. Since I'm running the LS2 and using the O2 sensors and all of the other computer stuff, I would get a code everytime I open them up. Guess that will save me a few bucks. Unless there is a work around?

[wayne petty]

I guess that puts a stop to my idea of installing a couple of cut-outs on the '40 Chevy. Since I'm running the LS2 and using the O2 sensors and all of the other computer stuff, I would get a code everytime I open them up. Guess that will save me a few bucks. Unless there is a work around?

you can do cut outs....   just after the first set of oxygen sensors....

are you planning on running cats???

[teal32]

Yup, already have them in place. The LS2 and 4L65E were a complete drop out. I used everything that was already there, from the cats to the computer. I went with the dbw. Using the cats and still running thru the "loud" mufflers made the other half happy. She can now listen to the radio and talk while cruising. And, the hot rod still makes a good sound. It was a win-win in that category. I just want to add the cut-outs to have fun with the rice burners. I thought it would be fun when they pull up beside me at a light and rev their engine. I'll just reach over and hit a button and the elec cut-outs will become "active". A couple of taps on the go pedal would bring a smile to my face. LOL I guess I have too much time on my hands.