P0451

[FirestormFRS]

Keep getting this infernal code and can't figure out why.

Mods
KW C30 kit
Skunk2 Header
OP/FP/CBE

Clamped the vacuum hoses under the intake but I'm still getting the code generally after I drive a bit and park the car come back and the DTC is there. Any suggestions would be greatly appreciated.

[SPCorBUST]

There is a thread on this code with multiple fixes including gas cap, hose clamping under the manifold (guess you can rule that one out), and determining if it's tune based.

Have you tried flashing back to stock and driving around below boost in low rpms for a few days? You could temporarily remove your cogged belt if you want to check the higher rpms as well. If it doesn't come up, the issue might be the MAF.

I think you could also try switching MAFS with a buddy and seeing if it goes away for you and pops up for him. That would expose the sensor as an issue but not if it's related to leak at certain rpms.

[Gopherboy6956]

I am also throwing this code. I Just swapped in a used FA with 8k on it after I blew up mine. Nothing special, 3bar MAF, 'stock' perrin Vortech Tune, and Radium Catch Cans.

Ran the exact same setup for an entire year on previous engine, and double checked all connections and hoses. Nothing changed with my filler cap - haven't gotten gas for over a month (Car sat for about 3.5 weeks while I dealt with engine crap)

Any ideas would be helpful.

Thanks!

[scionfr_s]

I got the same code when installed my Kraftwerks SV kit, just got tune update and hope no code again

[MattHoffman]

I am working with oft for a tune right now but, I still get it with my vortech v3.

[Gopherboy6956]

Yea i cleared it and it comes on once a month or so, maybe. Header related is my guess

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[nmastereal]

Originally Posted by Gopherboy6956

Yea i cleared it and it comes on once a month or so, maybe. Header related is my guess

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Why would this be header related. This strictly has to do with EVAP I thought.

[steve99]

@'

Originally Posted by FirestormFRS

Keep getting this infernal code and can't figure out why.

Mods
KW C30 kit
Skunk2 Header
OP/FP/CBE

Clamped the vacuum hoses under the intake but I'm still getting the code generally after I drive a bit and park the car come back and the DTC is there. Any suggestions would be greatly appreciated.

http://www.autocodes.com/p0451_subaru.html

Do you guys have flex fuel kits or aftermarket wideband 02 sensors using evap input to ecu if so get your tuner to disable P0451. As the evap sensor input has been re purposed

It just an emmissions code so just disable it , but it does indicate you have an leak in evap emmisions system or a stuffed evap sensor or the plugs loose or similar. If your not running a tune thats repurposed the evap input, but its not needed for engine running.

but will cause you grief at an emmissions readyness check

[Gopherboy6956]

Originally Posted by nmastereal

Why would this be header related. This strictly has to do with EVAP I thought.

Good point - I guess when it happens now, i just clear it and move on with my day. Could certainly be tune related.

I have no aftermarket fuel system changes, I do have catch cans though.

but yea, i just clear it and it will stay off for 1 to 2 months.

[brillo]

I have the moto-east flex fuel kit and I keep getting this code. I presume I need the tune adjusted to turn this feature off? Car seems to drive fine. Any issues with driving or logging with this code?

[Humphrey]

I recently fixed this problem on my supercharged BRZ. The problem for me was I installed a 11 BAR map sensor and the carb legal tune did not have its MAP scaled to the correct bar. A proper tune with the correct scaling fixed the code.