Need help for possible electrical issue

A6 All/ S6 All
#1

Hello,

I’ve been doing all the mecanical reparations myself, but now it seems that I’m having electrical issues, atleast thats what I think, and it is completely outside of my knowledge.

I have many codes, shown in the pictures, EPC light, ESP fault, meaning the car is in slow mode IF it starts. There is, sometimes, and during longer drives, a white smoke coming out close to the firewall in the passenger side engine bay that doesnt really smell like burnt oil or coolant (burning wires? short?) (valve cover gaskets changed 3-400 kilometres ago and no visible leaks). I possibly have a problem with my fuel system, which MIGHT be the cause of the fuel pressure regulator codes, but they appeared at the same time as all the other codes, and the car drove pretty much perfectly before.

I want to know if some knowledgeable people might point me in a direction before I bring it to a shop and spend big money for some possible small fixes (I hope)…

Thanks

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#2

Have you done anything related to wiring recently?

#3

No, the night it happened I just came back from a test drive after fitting two new fuel lines, but havent touched anything remotely electrical. After coming back from the test drive, it just stalled after like 5 minutes of idle. Completely out of nowhere

#4

Well, it is indeed strange. If you haven’t crushed any wires during manifold install, I’d guess your other options are

  • some kind of animal chewed up your wires somewhere
  • maybe somehow your ECU was damaged?

Check for all the ground connections you were near during fuel lines job - two on the fronts of each head. It could’ve been weak and you somehow damaged it more.

If nothing visual comes up, I’d start with erasing your fault memory, and checking which ones come back on the spot, with only ignition turned on. If you do, report what happens and we’ll go from there.

#5

Both grounds were tight and the wires seemed undamaged.

After clearing the codes and turning the key in accessory, no codes showed up.

#6

Ok, try to run the car now in order to see if they come back, and if so, at what circumstances. Keep an eye on that smoke you mentioned though.

#7

When I crank the car, it will start, then after a couple of seconds stall. All of the codes shown above come back.

#8

Smoke is only present after a long drive. Maybe its just a coolant or oil leak onto my manifolds, as its pretty hard to see down there with how cramped it is, but I dont think it smells like either, and even my friend thinks it doesnt smell like it. It has more of a burnt smell…

#9

Would you be able to do a VCDS scan, or a scan with some other tool which will show freeze frame data?

Also, check your fuel pressure readings. From the codes you are getting i’d say stalling might be related to the fuel pressure fault, or the maf sensor fault.

#10

There are many error codes. Lets work backwards. How long have you had these error codes? The MAFs on both sides have issues. The MAF errors give you the ESP and TC faults. There has to be something electronic going on. As that many error codes on both sides of the motor are not very likely.

#11

Ive found a thread, really randomly while I wasnt looking for solutions about that, but the guy had an extremely similar situation and almost the exact same codes, and he too thought it was an electrical issue and dabbled in fuses and relays.At the end of the day, the only thing was either his HPFP or fuel pressure regulator/sensor, it isnt clear. Ive ordered the fuel pressure regualtors/sensors since they arent costly, and will try with that and see what happens.

Here’s the thread: https://forums.audirevolution.net/t/s6-c6-2006-5-2-v10-air-flow-fuel-pressure-errors/18459

#12

Awesome. Keep us posted.

#13

Changing the regulators did help in starting the car. Now I can start and drive, but I cant go above 3k rpms or the car will trip out like its not receiving enough fuel. I think one of my HPFP is finished. I will have to buy one and see.

Anyone knows a site where you can get a good OEM or hitachi hp0029 HPFP for relatively cheaper than the normal prices? 800 bucks on average for a pump is pretty wild…