Hey guys,

I'm at a loss and ready to get rid of the lemon I bought for my wife. It's a 2013 Audi A4 quattro with the flex fuel 2.0T. It has 69,000 miles. When we bought it, it had a check engine light with codes P2293 (N276) and P12A4. I'm pretty mechanically inclined, but i'm not the greatest when it comes to german engineering. Trying to fix this thing myself, so I've replaced the N276 valve (High pressure fuel pump), the cam follower, plugs and coils with R8 coils, the orange high pressure fuel sensor in the hard to get to spot, and the complete low pressure fuel assembly in the tank. Checked for pinched fuel lines, leaks, etc.

The P2293 code states "N276 valve, fuel pressure regulator mechanical malfunction." To my knowledge, the N276 is the fuel pressure regulator built into the HPFP, which I've replaced with genuine Hitachi. I replaced both the high and low fuel pressure regulators just to be sure, and everything I've yet to replace still hasn't fixed the issue. So i started looking into wiring. The harness plug for the HPFP gets 8v on the positive, and 3v on the negative. I thought maybe the ECM was backfeeding voltage from somewhere and causing the regulator to run on less than required voltage, but i feel like the voltage fluctuates based on how the fuel pressure should be regulated, and Audi does that by backfeeding voltage through the negative in order to drop the positive. Back to square one.

So I'm in need of some help/ideas. The only thing i can think of now would either be the low pressure fuel pressure sensor on the rail, or the injectors could be clogged causing a pressure reading less than called for. Do i keep throwing money at it, or sell it as-is? Did i go about troubleshooting the wrong way? Please help. Sorry for the long post, and thanks in advance!