Audi A7 2015 Difficut to Restart

[Caesar]

Hi All

My son's Audi Quattro A7 3.0 TDI 2015 is very difficult to restart after running the engine. When after a run and engine is stopped, if He tries to restart the car the engine cranks but does not start! If he waits a few minutes and cranks it starts immediately. Car has been regularly service no Engine Management Lights and had it scanned with CavComm but no fault codes!

Anyone have a clue what the problem maybe?

Many Thanks

Caesar

 

[Burnerman]

This is so typical of a failing crankshaft position sensor - and they don't throw up a fault code either!
Typically, the cold start is instant, every time and the engine behaves perfectly until it's switched off.
Then, when hot, it won't start for love or money but once cooled down a bit its playing ball again until the next time.
Unfortunately I don't know where it is on your V6 but they are typically mounted on top of the bell housing so the thing can look down at the flywheel.
John

 

[cdbe]

Agree, my diesel used to just stop and not start again. By the time I'd killed myself pushing it somewhere safe it would start again perfectly.

 

[Caesar]

Thanks John and CBDE. You could be right as cold start immediate but even switching off and then back on again immediately it is difficult to start again!