That's weird that the problem didn't come back. Has the mileage changed at all? This thread might have some useful information for you. Po171 Cel - Factory 2.0L Turbo Powertrain - NASIOC

 

I drove it roughly 11 miles today. I didn't push it because just in case it was still running lean, I didn't want to damage anything. But the CEL never returned. Thanks for the link. I will check that out.

 

i get this code sometimes and i know it's my front o2 sensor. When I took it to Mastro they showed me the o2 sensor and it was all spliced up. It would be weird for your o2 sensor to be bad but it still maybe faulting at times. I haven't fixed this issue yet. I just reset the ecu and it runs fine. Hope this helps.

 

Well it happened two days ago and the CEL hasn't come back yet. So hopefully I'm good.

 

just to let you know...this happens to me as well. it will go away for about a tank of gas unless i'm driving long distance, but it still comes on..i hope you don't have anymore problems though.

 

LOL, yeah I hope I don't have to worry about.