Q7 - Injector bolts sheering off

[Q7_newbie]

I bought a Q7 7 months ago its now just reaching 90000 miles. Within the past month two of the injector holding bolts have sheered off and the injectors have come out. 

 

1 bolt I can understand that there is wear/vibration that will eventually weaken and snap but 2 within 1 month is a little hard to understand. Any ideas on if there might be a separate problem that is causing this to happen? Is there anything inside the piston that could cause that amount of force to rip the injectors out?

 

Please any one got any ideas, willing to try anything dont really want the other 4 to go as its £500 a pop after getting an engineer to pull out the other half of the bolt in the socket.

 

Cheers.

[Audi Owners Club.]

Sounds very odd...never heard of this before.

Can only imagine that someone has taken the injectors out beforehand and overtightened the bolts.

I would replace the existing ones that haven't yet snapped with genuine Audi bolts just in case

Let us know how this progresses