OBD II code PO171
 

Car is 1996 Volvo 850R Automatic transmission and the reoccuring code is PO171 - system too lean bank I. I had changed the front O2 sensor for other codes 3 months ago.

Any ideas? Thanks

check this link http://www.obd-codes.com/p0171

Always change both O2 sensors at the same time.

Thanks for the link. I will try these suggestions. The reason I didn't change both O2 sensors is replacing one took care of my problem before.

I will keep you posted.

This link suggested to use brake cleaner to clean MAF but I used only MAF cleaner.
Glad to help

Only use maf cleaner!!!!

Don't use aggressive cleaners such as brake cleaner to clean MAF.

Check the vacuum line that goes to the elbow on the passenger's side of the intake manifold - my bet is that you have a vacuum leak.

...Lee

I cleaned the MAF with electronic contact cleaner and it seemed to help but it was still idling inconsistently. Over the weekend I replaced the crankcase vent system and checked and replaced several vacuum hoses. I found a crack/rot on the bottom side of the short hose(this short hose also has a hose coming off it that goes to the AIC valve) that connects the throttle body to the turbo pipe. After I put everything back together now I have code PO 103 (MAF curcuit voltage too high). The car is very sluggish and actually cuts out under load about mid range and stalls now. Could this crack hose cause this? Please advise.
Thanks

Then probably you need to replace the whole MAF.

Well this thing started as a PO171 code and as it turned out after I replaced the intercooler hose to the throttle body, several vacuum hoses, and the crankcase vent system I think and hope I have solved that one. The car did much better after I replaced the cracked intercooler hose but still had severe stalling sometimes. I also had no codes.

I think I read if unplugging the MAF makes the car runs better then it is the MAF that needs replacing. Well it did that and it ran very good but would not idle very well and I also had PO102 MAF low input signal. I ended up cleaning the MAF sensor with electrical contact cleaner and it runs very good now. I will keep you posted if something else pops up.
Thanks for the help.