Okay so i have a 2004 Sti with about 72,000 miles on it and cel just popped up P0171 so i go to my handy dandy wrxatlanta forums to solve my problem. At first glance it didnt look to bad but the more i read the more i worried hnoes: about other problems that people had with this code and was wondering if i should just take it to the dealership or if someone could do a thorough inspection of the situation im having right now. it seems like its running fine now but i'd rather be safe than sorry. Thanks and sorry if this is in the wrong spot
could be lots of things, vacuum leaks/exhaust leaks/individual cylinder misfires/etc take it to a SUBARU SHOP close to you. if none close, tow it to Allpro
I think the closest dealership is 90 Miles away as for mods i have a k&n intake ap cobb tuner AP TBE but nothing has changed for a couple of years and this just came out of the blue.
I'm afraid nothing more than what was already posted - I would trust AllPro for expert help above anyone else (including a Dealer). If you can't get the car to Allpro, the dealer is your next best bet.
i had the same code on the my '04 Forester XT about 8 or 9 months ago. found out it was the 'AVCS Banjo Bolt filters" that caused my issue. I pulled the banjo bolt filters and reset ecu. All is fine now! but, i'm not sure the 2006 STI's had the AVCS banjo bolt filters. Joe
Could be a number of different things: IACV, o2 sensor, MAF sensor, bad hose/leak, etc. Try cleaning the MAF first...here's a write up on iwsti http://www.iwsti.com/forums/how-install/171272-mass-air-flow-maf-sensor-cleaning.html