The fuel pump behind the Driver's seat developed a serious leak (Recall Item), however due to scheduling I attempted to replace myself. Battery disconnect, pump replaced, battery connect, and drove for 1/2 mile. Next day only Crank/No Start and pump is silent. Brakes, oil change are as deep as I've dove into DIY. Feel way over my head and my awesome VCDS scan tool should be in the hands of a more competent soul. Work has me traveling so this drama has been going on for a few weeks. Desperately need some wisdom. Read a lot of threads and watched every YouTube video to try and solve myself. I surrender.

I've attached the Scan info and thanks in advance to anyone that has the time to review.

 

It's difficult to screw up an Auto-scan, even if you haven't delved into what VCDS can really do to help you out otherwise, so be of good cheer in knowing what you don't know. Since you replaced the pump

In your scan, and kudos to you for including it up front, it shows you got low voltage issues, which are made worse by some parasitic drain issues from known door handle sources, and low voltage causes so many issues on this car. 100 % YES, there is a fault code related to the fuel system, but it's not listed beneath the Engine Control Module grouping. You gotta go through to look at any/all fault codes. Easiest way to do that is simply click on each module highlighted in RED on the right side of scan page after it finishes scanning.

With the fuel lift pump, there is an electrical connector, and it must be snapped/locked in to hold the connection securely, so that's a point of verification. Here is the fault code thrown, but as it is an intermittent code that suggests it may just be a loose connector in the circuit, so again, verify anything you disconnected. There are multiple videos online of Crank - No Start scenarios where fuel lift pump/in-tank pump does not run, so take a look at those if you don't find a loose/problematic wire connection at that pump:

Address 17: Instruments (J285) Labels:. 4L0-920-KOM-V3.clb
Part No SW: 4L0 920 985 S HW: 4L0 920 985 S
Component: KOMBIINSTR. H35 0332
Revision: 00000000 Serial number: X2R51CLCE
Coding: 8BDF63040100CF05020205
Shop #: WSC 31414 790 00001
VCID: 44D14DFAEE9048CAEBF-8010

1 Fault Found:
00438 - Fuel Supply Sensor 2 (G169)
010 - Open or Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00101010
Fault Priority: 7
Fault Frequency: 3
Reset counter: 207
Mileage: 235108 km
Time Indication: 0
Date: 2025.04.12
Time: 11:08:01

 

Thanks for taking a look at the scan. After reading your response I replayed removing the original pump in my head. I struggled with "D" connecter on top of the pump and was in a hurry, big mistake. In hindsight, I think I compromised the locking tab on the connection since it seats but doesn't click to lock. I'll search for a replacement power connector to cross it off the list and I'm also going to hit the pump with a power probe to verify that it actually works since it's brand new.

Thanks again and I'll share the results.

 

Yeah, should be easy to verify since if it's good the in-tank pump will cycle once you push those connections together tightly and turn the key ON, if that's the only problem, etc. No need to get all fancy with probing it...low-hanging-fruit my friend. Keep it simple. If pushing the connector tightly together doesn't make it run, then you can 'jump-the-pump' to verify it's good, etc.

 

I just verified power to the connection at the top of the pump and all hoses etc. are in place and still nothing. Lift Pump is silent and no start. I need to fly a few people to a meeting so I’m tapped out until later this evening. I’ll regroup and rewatch all the videos on the topic.

I appreciate everything.

 

Hey guys,

So I have a similar issue here and there I get a crank no start, also getting a surging idle when at a stop and RPM's go up and down for about 5 mins before stopping. Turning the AC on helps and have noticed fuel smell when getting out of the car during a crank no start like something is dumping fuel.
Have been reading Reddit and other forms a lot of guys say Crank Shaft Position Sensor? Bought one but I can figure out where the thing is on a 2014 Audi S4 Premium Plus Auto I've heard below the fuel filter down in there but nothing online for an B8.5 showing where?
Much appreciated on any input or finding the location so I can try this new sensor to see if it helps?

Thanks,

 

Hi there!
Just FYI, you posted in the Q7 MK1 forum, so for advice/tips/research on your model and engine be sure to go to dedicated forum for it. Obviously, de-tuned versions of the 3.0T engine appear in lots of Audi models, such as the Q7, so there will be similar problems encountered across model lineups.

You need to do a diagnostic scan on your car; a full scan. Use a VAGCOM compatible scan tool (VW Auto Group = VAG). Always start off with the scan tool to see what the car can tell you. You need to get that fixed ASAP before something really, really expensive and bad happens, IMHO.

Search the internet is how you find archival threads and/or videos to help you out. The linked video shows the sensor is located beneath the car...not on top.:

https://www.bing.com/videos/rivervie...E156&FORM=VIRE

 

Would you happen to have any additional suggestions for my issue on the fuel filter pump? None of this makes any sense. I’ve watched every video on this topic on both VW and Audi and I did the exact same steps and didn’t touch anything else, but here I am. I’ve read at least 3 comments on a few of the videos where someone has had the exact same issue as me, but unfortunately no one replied to their comment. It’s never a good time to have a vehicle down, however we desperately need this up in running to transport our special needs daughter to therapy daily. I’m at a complete loss and mechanic is booked out. The only goodwill offer I can think of is offering 200.00 in AMEX gift cards to cover someone’s time with solving it. I’ve downloaded the service and repair manual and while it while be valuable in the future it wasn’t very helpful with this task. Just a desperate stressed out dad.

 

Have a gander at this thread chasing down the same exact fault code; there are some linked videos inside the thread, as well as a diagnostic/repair sequence, etc.

I think this may help you out:

https://www.audiworld.com/forums/a6-...fault-2839501/

https://fuseandrelay.com/audi/q7.html

 

Sounds good. I already have the fuse and relay page saved and previously printed, great resource. I’ve previously read the other post which I believe shows the tank access behind the passenger seat which I didn’t access during my repair, but I will reread. I just hadn’t thought that replacing the fuel filter pump behind the drivers seat would affect the components on the other side of the tank. You obviously understand the system far more than I do so I’ll take a look after I get everyone to bed. Pot of coffee already brewing. Thanks again.