2007 MS3 - Troubleshooting P2122 Code

Hello, all.

Unfortunately, I'm at a bit of a loss pertaining to an issue I'm facing with my 2007 MS3 and am hoping maybe someone may be able to shed some light.

I drove it last Sunday, Sept. 29th to my friend's garage to install a few items:

1. Upgrade the stock K04 to a BNR S4 v3
2. Install an XSPower V3 exhaust manifold
3. Install some OEM injectors that I had cleaned/flow tested + new o rings for them to go along with my corksport seals
4. Installed new serpentine belt pulley and tensioner
5. Clean up the coil pack harness as the loom was extremely crusty and falling apart
6. Load my base map from Rob F.
7. Oil change + replace lost coolant

The car drove fine there sure enough. The engine is an OEM reman with about 15,000 miles on it. It took us about two evenings of work to get everything changed out and installed. I removed the wiring loom from my coil pack harness as it was extremely crusty and falling to bits, visual inspection of wiring seemed fine, so wrapped it in some good engine tape to replace the loom that it had. Loaded my map and checked my AP. Saw I was throwing the code P2122 pertaining to the accelerator pedal position sensor reading low voltage input (it has never had that code prior), cleared the code, it immediately came back.

Tried starting the car, it cranks just fine and "starts" but immediately putters out and dies not responding to any throttle input whatsoever. HPFP pressure with key in acc position reads about 66 psi. When cranking it only goes to about 88 psi. I reviewed all the grounds nearby and connection to the hpfp spill valve and fuel rail + injectors, those seemed all plugged in and snug. I verified as well that the TB connection is snug and the red clip seems to be fine in holding it on.

Initial inspection of my fuses, I don't see any blown fuses immediately at least.

I've spent the past couple days investigating different options but I feel like I'm losing my mind over this.

Does anyone have any thoughts/opinions on what I might be able to look at in more detail? I feel like it's something that will wind up being an easy fix that I'm overlooking, but this one has me scratching my head thus far.

I'll attach a video in the comments as to what behavior it's exhibiting when trying to start. sorry this turned into a bit of a novel, I tried to be concise over what we looked at.

Thanks in advance!

 

Well, I feel like a fool (as expected) but the problem was something extremely stupid.

The fuel pressure sensor on the passenger side of the fuel rail was plugged in backward.

I think one of the clips was worn down allowing it to physically go on the reverse way and seem like it was on correctly.

Additionally, I had a powder coated valve cover installed and the cam sensor surface was also powdered, so I sanded that down as well.

The car fires right up now!

Always something silly.

 

Glad you figured it out!

 

I know this is an old thread but I am having the same issue and it’s not the sensors you mentioned as I have tried to unplug them and plug them back in. When ignition is on it read 66 for HPFP accel and when it cranks it reas 1400 then putters down like yours idk what it could be with mine