98CobraV6

So for about 2 weeks now my car has been showing the CEL on and off, it would come on every day and go off at night usually. I just got my x4 tuner in the mail the other day and accidentally tuned the car before I checked the engine light, so it cleared all the current codes. So, I have driven for about 4 days now (after tuning the car) and it just came on again and I was finally able to check the code and it showed P1131 "Lack of H02S11 switches - Sensor Indicates Lean (see P2195)"... My question is what can cause that to happen? I have noticed sometimes the idle is a little rough and I have noticed a bit of gas smell every once in a while at a stop light. Is it likely that I just have to replace my O2 sensors?

98CobraV6

I cant seem to edit so I will just reply;

It should be noted that I did have a dual exhaust installed they cut the stock Y pipe and put an H pipe there after the cats.. Im not sure if that would effect anything but I thought it might

Daehawk

Depends. Theres O2 sensors before and after the CATS. If they left the one off after it will throw a CEL.

dawson1112

Lack of upstream heated 02 sensor. Sensor 1 Bank 1.


This can be caused by a vacuum leak on the bank 1 side of the engine, or just a faulty heater in that sensor. 9 times out of 10 its a faulty 02 sensor.

98CobraV6

Okay thank you guys. The cars got 180k miles so I will replace the sensors as they're likely original and see if that fixes the problem. Thanks!