I was wondering if somebody can help me. I have a 96 850GL and I am getting a PO171 bank 1 system to rich error from my OBII computer reader. The car has about 90,000 miles. I checked the obvious things eg. plugs, air filter, etc. I was wondering if anybody experienced the same error and there is something obviously wrong with Volvos when they hit around 90K. Any suggestions? I am banging my head against the wall.

Thanks,
Clod

I've just been thru this with a 96 850. Couple of things to check. (1) your front (pre cat) O2 sensor may (probably is) failing. Volvo recommends changing them at 100000K anyway. (2) You may have a manifold vacuum leak that is "fooling" the front O2 sensor into thinking the mixture is too lean and it over corrects the mixture by enriching it. A major leak occurs at the rubber elbow under the theromostat housing. Bay 13 has good pics to walk you thru looking for common leak locations. (3) your ECT sensor (coolant sensor) may be failing that fools the control unit into thinking the engine is stone cold all the time. I'm ure these guys can think of other things. Good luck!

bl

Nope, I have no new information, just gonna second yours...it's usually the vacuum coupling, little rubber elbow by the intake. On occasion, it is the coolant temp sensor.

Chris