Contour Enthusiasts Group Archives Forums General Troubleshooting P171

My 98,2.5 contourhas been trouble free for the last couple of months.Last Tuesday my cel came on,since I was going skiing and didin't want to see it for the trip I reset the cel.Drove for 300 miles and no cel.Took it in after trip no codes present.On the weekend went north for the weekend,600 mile round trip no cel.This morning my wife started the car you guessed it cel is on.Took it in p171 shows up.tonight cel is off again.It has a new o2 sensor on bank one in December.was reading some threads about p171 being a vacume leak,but why is the cel now off?Any help would be appreciated.

The vacuum leak is coming and going.

Steve

I had the same intermittent vaccuum leak which acted up every time the weather got cold. Codes were p0171 & p0174.
I finally found it by spraying throttle body cleaner around the intake plenum where it bolts to the top of the intake stack. It disappeared shortly after detecting it.
I replaced the upper intake gaskets & have had no more codes for two weeks now. Codes would re-occur about once a week before fixing.

Hope this helps.
My car is a 96 mystique 2.5 24 valve

Thanks I'll try that,anything to get rid of this cel.