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check engine light :(


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so i was driving on the hwy the other day and I notice that my check engine light came on and i got alittle worried and tried not to boost alot or gun it and when i went home i hooked up my ap and checked for ce codes and none were found.. so then i decided to disconnect my battery to reset everything and so the light would go off. Then a week later it came back on and hooked up my labtop to my ecu and pulled up a learing view and it said that the code was p2096 meaning Post Catalyst fuel Trim System Too Lean Bank 1.. what do i have to do replace the mass air flow sensor and if so witch one.. headers down pipe? How do i get this light off!?!
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dansbiker, what's your *complete* mod-list?


What AP map are you running?


With post-turbo pipework-modified Subarus, P2096 is typically associated with the post-turbo O2 sensor, and is often elicited from displacing the rear O2 too far from the main exhaust stream, in an effort to avoid the more common P0420 DTC, via use of various "spacers."


Usually, aftermarket engine-management/remapping will disable (completely mask) the P0420 code, thus making the "overwhelmed" rear O2 sensor a non-concern.


Given that you're an '05, if you're still on your factory rear O2 sensor, it's possible that it has been compromised, and that a replacement will offer a cure, but that's taking a shot in the dark - jumping prematurely: BennnGeee's suggestion should help the diagnosis, as well as looking to see if your rear O2's output is within spec.


Also, if you have a V1 AP, remember that it may not pull all codes.


Historically, we've seen a few cases of rather mysterious P2096 episodes (i.e. http://legacygt.com/forums/showthread.php/p2096-help-103638.html?highlight=p2096), but most have been rather easily traced to the rear O2.

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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My fuel trim is fine .. i sent the learning view scrren to imfamous and he said everything is fine and he doesnt know whats setting it off.. and dont forget i've had all these parts on the car for about 20k
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Your mileage is low (like me :), I'm barely over 40K) - but there's still the wear of "time" on these vehicles. And like us humans, cars don't age like wine. ;)


Are you able to see if the rear O2 is operating within spec? In the in-link I referenced above, that OP's problems persisted when an aftermarket rear O2 was used, which the dealership was able to determine was slightly out-of-whack. Certainly, it didn't end his problems, but still, it's something first-line that I think you should look at. [ Honest question - something that's making me scratch my head, as I'm not a mechanic by trade :redface:: if the fuel-trims check-out, would that automatically eliminate the rear O2 and its harness as a fault? ]


If the tune and the hardware have been on the car for a while, and the car suddenly pops this code, I'd lead off with an inspection of either the rear O2 or its wiring harness.

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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  • 4 weeks later...

Any updates on this I have the samething happening on my 05 that had all the same parts for about 30k miles, I didn'thave any problems until I just installed my up pipe a few months back.


My set up

Perrin catless up and catless down pipes

Greddy Evo 2 catback

SPT intake

Stage 2 91 octane map on V.1 AP


I'm not worried about it actually being a problem or it causing damage. I would just like to stop throwing the light.

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I'm having the same issue right now.

Just bought my Legacy from my Dad about a week ago. Changed elevations and got the P2096 CEL code. :eek:

The mods on it are

Crucial shorty down pipe with divorced waste gate

crucial midpipe with flow catalytic converter

AVO axel back stainless exhaust with stock GT muffler cans

AVO top mount intercooler version 2

AEM cold air intake



Real time map currently loaded by way of AccessPORT as

06 TDC stg2 91 MT real

Reflash map is

TDC stage 2 MT


The original tuning was for 6000 ft elevation in Arizona. I'm now in Seattle, so I'm guessing that the change in elevation is causing a different air/fuel mixture. I emailed PDXTuning to request an upgraded map to put in via my COBB AccessPORT but am wondering if it would just be better to take my Legacy into a specialized tuning shop and get it on the DYNO. Have any of you had experience with customized maps emailed from PDXTuning? ;)

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