2005 A6 3.2 First indication of a problem I was driving at highway speeds and the engine cut out or jolted for a split second. It happened a few more times and these later times the check engine light came on. I was running on 1/8 of a tank of gas (I know, I know...bad) and this happened right when I drove from an area of 40 degree weather into <20 degree weather. I filled it up...same problem. I ran 2 bottles of Heat through it...same problem. Also,
I noticed sluggish acceleration and the instantaneous MPG indicated 19-22mpg going 60MPH when normally this car would show 29-31. I thought that the instantaneous MPG gage might be wrong, but when I checked the MPG between fuel stops on a long trip, it was 22MPG!

Took it to the Audi dealer and they diagnosed the error code as P2296. After troubleshooting (no fuel leaks on the lines or undercarriage, fuel regulators tested good), they stated they checked the fuel flow on the low pressure side of the fuel system and they said it was showing 3.5-4.5 psi and the specs say it should be at 6 psi. They said they thought it was either a plugged fuel filter or a bad low pressure fuel pump (LPFP) (the one located in the gas tank). I had them replace the fuel filter and recheck it...still tested at 4psi and they said it needed a new low pressure fuel pump ($550 quote). I said I would think about it and drove off.

On my way home, I noticed a remarkable increase in power during simple acceleration. I hammered it and couldn't believe the power. My instantaneous MPG was also back to normal - my car was fixed (so far)! I ran a can of SeaFoam through the tank for good measure. What do you think the problem was? I'm guessing just a blockage on the LPFP intake of some sorts - maybe ice since I was driving in <20degree weather? From what I can tell - the LPFP either fails and your car wont run, or it works. Is this correct? Thanks for any and all help...and I'll never run the tank below 1/4 again!

 

So it's not fixed. I started up the car last night in cold weather (<20 degrees) and it ran rough for a second or two before smoothing out. On the highway the low pressure problem was intermittent. I can tell when it's low because the MPG drops and the car runs a little sluggish. Ice in the gas tank which is plugging the LPFP intake when it gets below 20 degrees? It seems to run fine when it is warm. I've put two bottles of Heat in the gas and one bottle of SeaFoam over the last week.

 

Low pressure fuel sensor faulty, change that before you change the pick up pump.

 

There's more than one low fuel pressure sensor right? Should I just replace them all? Is that easy to do myself? If I replace the low pressure fuel pump in the tank I'm going to attempt it myself using this persons very detailed article to do it.

AudiWorld Tech Articles

 

There are two, both are on the engine. The high pressure side which is what your fault code is related to is in the v of the engine on the right side as you stand over the front of the car. The low pressure sensor is on the tank return on the left bank as you look at the engine.

It's a bit of a last attempt before pump replacement.

 

Thanks...ill replace that first. They're just plug and play right? Just unplugg and pop the new one in? Should i just replace the high pressure one?

 

You'll need to depressurise the fuel system before you take it off. Then yes should be straight forward to swap.

I'd change high pressure first as your fault code relates to high pressure side. Unless any other people have further suggestions....

 

I took it to the dealer in Chicago and they said re-tested the low pressure fuel pump in the tank and said it was running at 100%. It seems that the dealer in DesMoines (much smaller) tested the fuel pump in a way that applied to pre-2005 model Audi's. The Chicago dealer recommended replacing the high pressure fuel pump and since that was a job bigger than I was willing to tackle, I had them do it. It did the trick! The car now gets 29-30MPG on the highway and the power is back to 100% of what it should be.

 

Hi All,

2005 Audi A6 C6 3.2L here. Sorry to rez 6 yr old thread, but, I'm having a no start condition.

I replaced LPFP 3 years ago. (3 weeks later needed replacement FP module). I thought that was my issue. I had erratic power under full throttle and sluggishness recently. I cleaned up the coils of oil, and cleaned electrodes on plugs. Ran great! Test drove 3 miles, parked it for work the next morning. Next morning, Crank, crank crank.. no start.

I assumed it was fuel pump module issue again. I pulled seat and powered fuel pump in tank directly with Power Probe. Pump runs, No start.

I thought this system was semi returnless? Can you confirm there is LP fuel sensor under hood?

I'l looking to buy a fuel test kit, and I am open to suggestions on a sufficient kit.

I'm checking compression and spark when things warm up outside.

Thank you.