Tim Baker

Hey so continuing the saga here...
so far in the last month i have replaced the hpfp and the electric fuel pump. Prior to this it was the injectors. I have another post called saga of the misfiring a6 on this forum that outlines the history in more detail.
my current problem is this....
The car is stalling randomly.

i have scanned with vcds and gotten a code for g247 sensor short to ground.

i have checked the wiring to the sensor... fuses relays etc and they all check out.

at first i thought it was my transfer pump as it had been running poorly so i replaced it.

the car ran perfect for one day then the problem reappeared

Today i took it apart and checked the wiring and all seems okay. I just find it crazy my whole fuel system has failed in the last 1k miles!

so checking vcds measuring blocks it appears that the g247 sensor randomly reports 0 bar to the ecu for a second or two. This causes the engine to basically shut down and if i don't manage to hit the gas it will stall.

for the most part it idles okay but still gets the random stall.

it appears my g247 sensor on the fuel rail has failed or is in the process of failing.

i will have to get a new one from dealer and replace it and report back.

i also noticed that there seems to be too much oil in the intake im guessing this could be the oil seperator and will need to replace that while i am in the intake.

someday i hope this car will run perfect for more than a few hundred miles at a time.

my question is... is there something i should check that could cause all my fuel system components to fail seemingly one after another, or is it more likely the g247 sensor is just messed up and i misdiagnosed the hpfp and transfer pump.

while i know this can be caused by a faulty hpfp in my case i just replaced that and the transfer pump and the fuel filter with new from dealer parts... it seems unlikely the new hpfp also failed.

so if anyone has any advice thank you!!!

the specific code is 16577 fuel pressure sensor (g247)
p0192 - 007 - Short to GND - Intermittent - MIL ON

Tim Baker

here is a scope describing the fuel pressure readings i'm getting. as I said I've replaced the HPFP. the G247 sensor is over 100 USD I hate to replace it for no reason... any advice anyone?

yellow is fuel pressure actual, green is spec, red is engine speed. you can see shortly after it reports 0 fuel pressure for a millisecond it stalls...

Tim Baker

I found a disconnected vacuum line on the back of the intake manifold... after reconnecting it, I am hard pressed to get the malfunction to repeat itself. Its hard to say if this was the cause because it is so random one minute it is running perfect the next it is doing the fuel drop off ****. Anyways I will take it on a road test and report back.

Tim Baker

definitely was NOT the vacuum line... this problem is baffeling. I've tried a new G247 it didn't fix the problem... there is apparently a new one that has superseeded the old part, the audi dealer has it for 160 usd, but I hate to buy it if it is not necessary. the wiring seems okay. I found someone else with this problem on another forum that said the problem ended up being a camshaft position sensor... i tested those and they seem okay also. so, I'm stuck at this point.

Tim Baker

so I just happened to test my EGR valve since I had a new one that I never installed... that thing was faulty. I doubt it was causing the issue but just another thing that broke. I have never had any vehicles that have so many random failures! (as often) Anyways, I'm in the process of checking all the wiring, specifically the wiring from the g247 to the T14 connector and from the T14 to the ECU. I will run new wires if I find any anomalies.

Tim Baker

The new part fixed the problem. The part had a new part number according to dealer when i installed new hpfp i should have also replaced the g247 on the fuel rail with the superseeded part which ended with a c instead of an a.
i also replaced my egr valve at the same time but i gotta say the car runs and idles a whole lot smoother.

Jonlereux

Hello Tim,
What was the ultimate fix to your issue? Was it the G247 sensor? I have replaced HPFP, EGR Valve, fuel injectors, all coils, spark plugs, memoved the intake, checked for intake leaks, changed all sensors on the fuel rails, etc. without being able to resolve a similar issue. I am unable to get rid of a leak in the intake fault and a fuel pressure to high fault. I performed a smoke test and could not locate any leak at all

I am leaning towards a wrong part number/sensor that is not compatible with my vehicle but it just does not make sense, My car was running perfectly and just happened to latch a check engine light one day. I am now down a long rabbit hole attempting to resolve this issue without any success

Any help is appreciated

Tim Baker

I would check your ECU or control module at this point. It's been a couple years now since i sold my c6. My issue ultimately i believe was the fuel injectors, but i'm not completely sure. I did quite alot of work on that car including rebuilding the heads. have you replaced all your vacuum tubes and does it hold vacuum? if so then there must be a sensor at fault. I seem to remember this G247 sensor being a small thing that fixed alot of problems for me, but unfortunately can't remember what any specific solution was beyond what may have been documented in these threads. I wish I could help you more! Best of luck.

Jonlereux

Thanks for the reply, I am at a loss at this point since it went from running with no issues to running like dog crap. I will be looking at vacuum lines next. I would hate to find out my ECU is the culprit, but it would be my luck.

Tim Baker

Have you taken your intake off and examined everything? The oil separator under the lower fuel rails is a pain to change but it can cause some wierd issues. When you say running like crap is it misfiring what are the specifi symptoms? do you have a vcds scan?