T6 - turns over but won't start

[Oges]

T6 - 2016 - 204bhp. 145K miles and had it from new and FSH

About 3 weeks ago I came back from Bristol (about 150 mile trip) and the next morning it turned over but would not start. I called the AA out and he plugged his diag in and it showed no codes but he tried it again and it started. I drove it to the garage and they had it for a week and couldn't find the problem but noticed the same thing that if you plug in the diagnostic you get about three starts out of it until you have to do it again. So I'm at my whits end now and have bought a £20 diag off amazon which is doing the trick and its pretty consistenly every third start . Anyone any ideas ? Thanks

 

[Dellmassive]

Assuming it's fuel related?

Not heard of any diag connection making things work.

Fuel lift pump?
HPFP?
Low compression?
Leaking injector?

 

[Sasquatch]

Try the spare key. Probably not it, but it costs nothing to try and has caught me out in the past.

 

[Oges]

Assuming it's fuel related?

Not heard of any diag connection making things work.

Fuel lift pump?
HPFP?
Low compression?
Leaking injector?

No, The AA guy and the garage have never heard of any diag connection making things work either . But it does seem to work. It runs fine once it starts also.

 

[Oges]

Try the spare key. Probably not it, but it costs nothing to try and has caught me out in the past.

Hi. yes I tried that in the first instance as I thought it may be immobiliser problem.

 

[StratosFearXX]

How bizarre, following.