I pull the car from storage after month and a half,stupid 100 inches of snow..shut off eng light with 171 code,go to get haircut 3 miles away..come out and light is back on,already looked for vaccum leak,new plugs wires,o2 sensor maf...not GM ...what could set it of so fast...

 

is there a o ring on pcv on s/c cars?

 

supposed to b,e. but I didn't get one when I bought pcv either
how did you look for vacuum leaks

 

Did you change both O2 sensors? Was the car outside in the snow above the level of the gas cap? Even a small amount of water in the fuel can cause a lean exhaust to be indicated. The PCM will clear the MIL after the third consecutive passing trip. The history DTC won't clear until there has been 40 consecutive warm-up cycles.

 

I but I only changed the upstream 02 sensor I sprayed everything for vacuum leaks had a vacuum gauge on it and read 19

 

I think I found it,the vacuum that was supposed to be connected to map sensor was not connected...well it didn't seem like it,found plug off,so far I drove to get gas and few other places and it didn't come on...gross fingers.

 

cross*

 

Congrats! That'll do it. Let me know if you still have probs. Got other tricks to try.

 

It has not come on yet and I've driven a lot of miles hopefully that's the fix

 

today the light went back on after 4 days...