It's probably something so dumb, help!

A6 All/ S6 All
#1

Hello,

2 months ago I changed the high pressure metal fuel line going to the passenger side HPFP cause I bent it while removing my IM once (oops). It drove great after replacing, and after coming back from the test drive, I let the car idle in the driveway, and after 5 minutes, it just stopped. I couldn’t get it running, it wouldnt even crank.

At this point, I thought it was the JHM tune, who, for some reason, deleted itself, so I reflashed it on the spot, and managed to get it to drive long enough (extremely roughly tho) to go back to my house (I was at a friend’s). As I pulled up, it died on me again, same thing.

At one point, the situation stabilized, and I could start it again, tho it would stall by itself the first start, and the second it would idle, tho roughly again. If I try to rev, it would choke itself, like fuel or air was missing, Pulling up the codes, there were many seemingly unrelated codes (as shown below) leading me to believe to be an electrical issue at first. But a couple days after, I found a post on this forum where a guy had almost the same exact codes as me and the same symptoms, and what resolved his issue was a new HPFP. That’s what I did, and nothing changed.
IMG_0210 IMG_0212 IMG_0214 IMG_0211 IMG_0213

It was winter, and with my issues, I just decided to store it this winter and resolve the issue when I pull the engine this spring. But a couple days ago, something clicked, I thought about the fact the I replaced the battery a bit before everything started, but I never coded it cause I didn’t have VCDS. In the meantime I got it, so I just coded it. But again, nothing changed. Here’s the full VCDS scan after coding the battery. If some of you have any ideas, do tell, I have nothing to lose, and I do believe its a dumb problem.
(extra info: I did mess again a bit before everything started with the fuel filter since I bought a new one, but I couldnt get it off cause one of the clips broke in my hand. I did mess with the lines for a long time to try and get it off, but it was unsuccessful. Could this issue start from a small leak from or a faulty fuel filter??)
vcds codes 10 janvier.pdf (166.3 KB)

#2

Do all of the codes come back after you delete them?

#3

Yes, thats after clearing them

#4

It seems to be wiring related to me. Are you sure, you haven’t damaged any wiring during repair?

You can try unplugging MAF sensors to check, if it will start.

#5

It really happened after replacing one of the hard metal fuel lines. Thats why I was so focused on the fuel pump part at first. I dreaded the wiring being the issue too. But no I didnt touch any wiring recently. I will pull the engine this spring when it will be warmer like I said, so at that point ill inspect the wiring. Tho id like to get it running normally before pulling the engine, so I know when I put it back in the car that its suppose to run good and if theres any issue, its because I missed something putting it back

#6

I looked at the vagcom printout and a few things jumped out at me. The codes all show voltage well below 12 and terminal 30 is showing 0 volts. I would suspect a bad battery, alternator or wiring. I’m definitely not an expert, but I don’t think that not coding the battery would cause those issues. I think the coding just changes the charging of the battery based on age. I don’t think this electrical issue is related to the fuel line; it’s probably coincidence. My two cents.

#7

I would fully charge the battery and see if that fixes it. FWIW, I keep my car on a tender all the time because these seem so sensitive to voltage.

#8

It isnt the battery, I already made sure everything was fully charged and all. I havent checked for sure yet since my car in under a blanket covered in ice, but I think I found the issue. Its a fuse that blew which all of those codes you see are connected to it. I will check once its warmer outside. That fuel line tho may have played a part in the blown fuse since this fuse blows most of the time when the fuel pressure regulator on the HPFP asks for too much voltage, then blows the fuse, which might have happened because me replacing the bent fuel line freed up some more fuel pressure and flow…

#9

Ahhhh, interesting. That does seem plausible. I wonder if the draw from the fuel pump is causing the voltage drop too?