A5 Intermittent Failure to Start

[FurtiveSway]

Hi all,

got a 2011 A5 Coupe (Black Edition/S-Line) with a 2.0 TDI engine (156,000 miles).

Back on the 15th April - She was cooling down in neutral after a drive when all of a sudden it stopped running. I tried to restart it and it wouldn't work. Cranking but no ignition. Car was brought by recovery truck to my local mechanic who said it showed no codes or anything obvious. Battery was fine. They suggested it could be to poor quality fuel and replaced my fuel filter. The car restarted for them every single time, not an issue.

It has been perfect for a month and just last night it did the same thing. I was moving on an incline in 1st gear before it vibrated and broke down again. Unable to restart, cranking but no combustion. I had to abandon the car overnight and came back this morning and pressing the accelerator while restarting I managed to get some life after 6-7 cranks. I managed to drive it back to the fore-mentioned mechanic who is stumped. No codes, something is showing low voltage but he's unsure if it's related.

Any ideas guys?

 

[Paul V.]

I had a similar issue with an older A4 B5, and we found under the hood a loom of cables eaten by rodents. When looking under the hood do you see anything obvious? How often was the oil and filters changed?

 

[FurtiveSway]

Hi lads,

thanks for your replies.

Had the A5 with my independent mechanic again for 2-3 days. He daily drove it, it never repeated the issue. No codes, nothing of note.

He suggested I bring it to Audi who had it for 2 days. Again, they found absolutely nothing off, no codes etc again. They drove it 70 miles over 2 days and it didn't miss a beat, was told - ''one of the best condition 150k mile cars we've seen.'' Great to hear but no solution in sight. My car was due a recall on a heater element which they replaced free of charge as-well.

My gut instinct says fuel pump but will they always show a code? My mechanic thinks it's the high pressure one but I don't believe there was any loss of rail pressure on it.

 

[FurtiveSway]

Well - Audi has had it for 2 days and couldn't re-create the issue.

So got the car back with no peace of mind. Worse still, some ****** broke my windscreen over the weekend.

 

[pelhamsdetailing]

I would personally put that down to a possible cam sensor issue. A faulty one will give you all of these symptoms, although I'm surprised it didn't get flagged on the scanning software used.