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2005 Subaru Outback 2.5 Turbo
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35 Posts
Discussion Starter · #1 ·
Hey guys. I had a shop replace 02 sensors on my 05 outback XT, as well as a radiator hose with a slow leak. Now after a couple weeks of driving, Im getting an a P171 error code. I checked all my intake connections, look good. I didn't get carburetor spray yet to test idling. Im wondering if the tuning needs to be reset/releaned after new 02 sensors. Not sure if the shop did that or if its even needed but Im not sure calling and asking would help, sorry I don't trust shops and only use them when I am too busy or think that I have something narrowed down.

Appreciate your input.
 

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Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
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15,899 Posts
Is this car tuned? Or is it stock?
How many miles?

Stock ECM doesn't need any kind of reset when changing parts. It'll figure it out. If the battery was disconnected a throttle relearn is usually needed on this generation, but that would only effect shifts with an automatic and curb idling until the computers relearn while it's driven.

Did you install Denso sensors?

A bad AF sensor could cause a lean code to pop up. Looking at data for the AF sensor, Rear O2 and STFT, if the STFT is way high and the Rear O2 voltage feedback stays over .9V, while the AF sensor remains at Lambda, then that would point to a bad AF sensor.

Otherwise you could have a dirty MAF sensor, weak battery, bad grounds, vacuum leak on the front of the turbo or boost leak after the turbo that is allowing for air to get sucked in when the engine isn't under boost. Then there's a leaky BPV or it's gasket, leak in the intercooler, leak at the throttle body, the bypass hose is bad, cracked PCV valve, shite brake booster, or anywhere air can get in to the engine and it's not metered.

Smoke test and put 20 psi pressure on the system. You'll find it.
 

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Registered
2005 Subaru Outback 2.5 Turbo
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35 Posts
Discussion Starter · #3 ·
Im not sure if it was tuned or stock. I bought it from an auction 3 years ago. Someone put some money into. Mishimoto radiator, aftermarket turbo, looks like some other stuff. Im not sure what kind of sensors they put in, probably the basic stuff. I shouldn't have any bad grounds as I cleaned up and tighten last year while I chasing something else. I just thought it was interesting it wasn't long after the new sensors were installed. Ill have to look up with the PCV valve. The mass air flow sensor looked good. I blew it out but I guess maybe I should spray it with cleaner. I have a scanner but it doesn't give that much information, just some basics. speed, boost, vacuum, faults, etc.
 

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Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
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15,899 Posts
I suggest you find a tuner. There are a few members on here that do it for a living and have time to work with you like @west_minist with XTreme Racing Tuning. An aftermarket turbo generally means someone tuned it. They would have had to tune it to match the dynamics of the turbo. If they didn't then they like to gamble.
 
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