[Ron G]

Hi all, not sure where to post this under. Had the check engine light, traction control light and flashing cruise light come on today. The check engine and traction light are solid with the cruise light flashing . Runs fine no power loss or smoke or leaking . I did plugs , air filter and serpentine belt about 75 miles ago. No issues up til now with the changes. Could it be something with having the battery out to do the plugs? Any help would be appreciated. Thanks Ron.

 

[sleepstate]

Need to have the code pulled and read, any auto parts store can read the code for free.
Won't be able to help at all without knowing what the code is.

 

[Ron G]

Thanks. Will go and have that done. My son had a similar situation on his 16 WRX with 42k on it. Over $2k to replace the computers. Ouch!! Hoping for the best. Ron

 

[Ron G]

Hey all. Been a busy week, but who hasn’t had those lately? I had the code read and it came up P0171. Mass air
Flow sensor. Subaru #22680AA380 197400-511. Denso. The Subaru part is about $150-175. Auto zone had their replacement versions at $125ish. Anyone used anything they can recommend? Or ones to stay away from? See knock offs from $20-45. What’s everyone using? Thanks. Ron.

 

[2.5x_sleeper]

@Ron G how did you decide it was a bad MAF?

P0171 SUBARU - System Too Lean Bank 1

Possible causes:
• Intake air leaks
• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Faulty Mass Air Flow (MAF) sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]

 

[TMX]

+1 How did you figure out it was the MAF sensor when it could be a few others?

Anyway, you want a cheaper but definitely work MAF sensor?
https://www.rockauto.com/en/catalog/subaru,2011,forester,2.5l+h4+dohc,1447439,exhaust+&+emission,mass+air+flow+sensor,5128
Denso are who make the OEM sensor.

Yours could ofcourse just need cleaning with MAF cleaner though.....

 

[Ron G]

Hey guys. I had the code read at my local auto zone. That’s the only thing that came up when he uploaded the read into their computer. The guy who did it had a 12 outback in the lot and he said he replaced his last year on a P 0171 code he got.
Looking at the list of possibilities, the Pcv hose would be obvious. Lack of fuel and ignition misfire don’t fit the bill as it seems to be running fine. Could be wrong tho. Wouldn’t the faulty injectors and incorrect fuel pressure lead to a rough running car too? I’m not sure the new maf sensor will fix the problem either. Could it just be dumb luck that the auto zone diagnosis was right? Thoughts??? Thanks for the replies also. Ron

 

[Ron G]

Sorry for the long wait for the update. I did replace the MAF sensor (rock auto denso) along with the PCV valve about 800 miles ago for the P0171 code. I haven’t had the CEL come back on so I think those were the problem. Hope this info will help others out. Thanks for the help from all who replied. Ron

 

[Ron G]

Another Update

Hey all. Car was good for 800 + miles then on came the Cel again. Same lights and such. I bought the denso air/fuel sensor off the big A store for about $93. Put it in and within 125 miles the lights reset themselves. Aye!!! Time for this to be done. Thanks Ron