Rubyz Posted January 18, 2021 Share Posted January 18, 2021 (edited) Hey everyone. 2007 Legacy 2.5 Non Turbo with 59,000. So had this code off and on for about a year. P0171. First time I made a smoke machine to find intake leaks. Found a massive one. Someone put 2 wood screws through the airbox at the TB to hold the internal baffle in place. they missed a couple times and neglected to fill the holes or seal the screws the used. So I installed a new air box. Double checked all clamps were tight. No dried out vacuum hoses that I see. Code was gone for 4 months! Then it cam back. Monitored the upstream O2. Was very lazy to respond and stayed closer to lean all the time. Installed new O2 sensor. Cleaned MAF. 3 weeks later, dang code is back!. Tried smoke machine again. Noticed just a trace of smoke from EGR valve where solenoid bolts to valve. Could this cause it? Maybe when EGR is not flowing?? I would think I would hear an exhaust leak when EGR was flowing. Maybe not though. My first Subaru. AM I missing something obvious? Scott Edited January 19, 2021 by Rubyz Link to comment Share on other sites More sharing options...
Rubyz Posted January 19, 2021 Author Share Posted January 19, 2021 So this morning, my son drove the car to school. He said when he left car was running really rough and could hardly gain speed. He said he had it at about 50% throttle and once he was able to reach approx 20 mph, it came out of it and ran fine. No Check Engine light. On his drive home car was running fine. Check engine light came on about half way home. P0171 DTC again! I grabbed some pics of Freeze Frame data and attached them. Link to comment Share on other sites More sharing options...
apexi Posted January 19, 2021 Share Posted January 19, 2021 Just to double check, did you clean the 2 maf wires that are up hidden inside the sensor? https://legacygt.com/forums/showpost.php?p=6010958&postcount=8 Link to comment Share on other sites More sharing options...
Rubyz Posted January 19, 2021 Author Share Posted January 19, 2021 (edited) Good question apexi!! I could not remember so I just went out and pulled the sensor out. I do not think I cleaned the ones way up in the sensor. Was looking at it like a GM one where everything was exposed. I am guessing I just cleaned the exposed wire that is probably the IAT sensor. After closer inspection it looks like one of the actual flow wires is corroded!! That would explain it thinking it had less air flow than it did and injecting less fuel there by having a lean mixture. I should mention the car sat in someone's backyard for a few years with a spun main bearing before being rescued and rebuilt. Definitely makes sense. Don't think I can clean the corrosion off with cleaner so it looks like a new MAF is in order. I will try cleaning first. Thanks apexi!! Edited January 19, 2021 by Rubyz Updated info Link to comment Share on other sites More sharing options...
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