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2012 Forester 2.5X Non turbo- Code P0171

Hello Guys

I am new to this forum and this is my very first forum post . My 2012 forester has only 50,000 miles i got check engine light code P0171 with steady check engine , traction control light and blinking cruise control . I took it to Auto zone to check the code and it shows P0171 system too lean (Bank1) and suggest MAF sensor. I clean it thoroughly first wth MAF cleaner and reset it by disconnecting negative battery terminal light came back on after 7 miles, than I replace MAF along with PCV valve , this time light came back on after 16 miles . Most recently i replaced fuel tank gas cap along with new FRAM airfilter and again reset it by disconnecting battery terminal this time light came back on after 214 miles on highway when my fuel tank was nearly half empty, Also i notice little shacking at very first start and also fuel consumption increased by around 15-18 percent. please note my car is out of warranty and dealer here in Michigan is asking 140 +tax for diagnostic only.Any help will be greatly appreciated..
 

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2012 Forester X Auto
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Hi @VickyLari -
It may be that you have an injector clogged.. Just guessing.. If the injector can't deliver its rated fuel, it can run lean. If you want to try something yourself, a bottle of injector cleaner isn't expensive.
Otherwise,
I would suggest you find a well rated service shop that specializes in Subarus.
Their rates are typically a lot less than a "stealership", and unlike a dealer, they don't get clients from their sales department - They have to be good or they are out of business.
Good luck.
 

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Discussion Starter · #3 ·
Thanks DragonSubie7, I will definitely try that, just curious it is the one Autozone sells in plastic bottle and you pour it with gas tank fill.?
 

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2012 Forester 4 speed auto
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First check that no unmetered air is entering the intake manifold. Check that the exhaust manifold is sealed too.
 

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2012 Forester X auto
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For me it was the A/F ratio sensor.
Tried a few other things first that everyone suggests (MAF sensor, PCV leaks), but A/F sensor worked. That's the oxygen sensor upstream of the catalytic converter. Denso 234-9109, $110 from Amazon prime seems like best deal.
 

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