Hello Everyone, finally bought an S4 that i've been wanting for so long. Unfortunately i'm having some problems with the MIL. When i bought the car the previous owner offered an MTM chip which i took and drove around for a few days. After the second day my MIL light came on and i got the codes P1176 and P1177. So i told the guy something is wrong with this chip i don't want it any more and we swapped it back out. The light went out and i drove it for a day. The light came back on and now i have 4 different codes. P1176, P1177, P0159, P0302. I looked up the codes and I'm just wondering if there is one problem causing all of these codes. Any ideas on where to start or how to fix it? This is real problem since i have to pass emissions to get a tag and obviously not going to pass running like this[8D]. Thanks for the help.

 

P1176 - Bank 1: O2 correction behind catalyst: control limit reached
P1177 - Bank 2: O2 correction behind catalyst: control limit reached
P0302 - Cylinder 2 Misfire Detected
P0159 - Oxygen Sensor Circuit Slow Response (Bank 2 Sensor 2)

Sounds like the cats are gutted or the downstream o2s are bad and possibly one upstream o2. You may want to check the catsoutor ask the guy to either fix the CEL or make him put some cats on if he did indeed gut them.
I know we all do it but it IS illegal and selling someone a car without divulging such information is most likely unlawful.

 

The car was running fine when i purchased it. The chip wasn't installed on the car until i bought it. Is it possible the oxygen sensor is causing it to misfire which is causing the other 2 sensors to be overloaded?

 

yes it might cause it to misfire because the car would be running too lean and then the computer might not decide to dump fuel in the very second it registered running too lean, or it could just need new plugs or wires. You also have got to check like red said about the exhaust setup and what he did with the pre cat o2's and if he relocated them and did it right at the same time.

 

Just test &/or replace the O2's, stuff like this is going to pop up randomly, get used to it....

 

Well i'm used to working on engines but never one as tight as this one. Clue me in on how to test the sensor. If I need to replace it where's the best place to get one? Am I going to cause more parts to go bad if I keep driving without fixing this? The car runs fine with the exception of idling a little rough. Thanks for the help.

 

Purchase a Vag-com from Ross-tech
Then purchase a Bentley manual for the S4
This is the ONLY way you can DIY anything, all the test & DIY are in there

Yes, if you keep driving it, you will damage other things....