Q7 TDI 2009 100k - Glow Plug light Flashing - Reset turn car off/on

A couple weeks ago my Glow Plug warning light popped up flashing. Immediately the car began to go in what everyone is calling 'limp mode', meaning no acceleration. I drove to my mechanic and they stated there was 2 faults (thru the reader) of something like "lean mixture" and "turbo issue". They did not have time to work on it in full, so just cleared the faults and check-engine light too. I drove it a few days then the Glow Plug Flashing popped up again. I pulled over and stopped and restarted the car. Whah-la, seemed to clear it ...until 2 more days later there it was again flashing.

Is it bad gas? ... was at empty when occurred 1st, but filled up and still issue.
Is it bad turbo? ... if so then probably a VERY expensive road to go down.
Is Turbo leaking ... is this expensive issue?
Is it just a loose vacuum/line/oxygen/? ... local mechanic gave it a visual but nothing obvious.

So I am trying to decide if I should take it to my Audi dealer to fix (where I bought it and serviced religiously thru 85k warranty, but now out of warranty); OR let my local trusted mechanic get his hands on a tdi diesel but not audi guru?

BTW, strange, probably unrelated, but I suddenly hear a click noise in dash when parked and push the brake.
Appreciate anyone's help and expertise.

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Update 16Dec - 1 week of running and GlowPlug light on again 1 time, but immediately cleared once restarted. 4 days all is good.

Update 16Dec - FAULT CODE = 299 ( P0299 ): Turbo Boost Charge UnderBoost

we'd need to know what the exact faults are before offering any advise. Obviously, everyone on here will say to avoid the dealer. If you have a TDI mechanic, you could give him a try

Im not going to presume to know much at all, but sounds like how my dads car was acting, turned out to be the actuator. But yeah, i entirely agree with yatzee

Well i would bet it's (in order of likelyhood)
1)Bad gas
2)Glow plugs are faulty or wiring is melted
3)Turbo re-circulation valve is leaking
4)Turbo needs to be rebuilt

We had the same symptoms. They replaced injectors.

Similar problem 3 weeks later. They replaced the high pressure pump.

It has been solid since then.

Gluca said:

Well i would bet it's (in order of likelyhood)
1)Bad gas
2)Glow plugs are faulty or wiring is melted
3)Turbo re-circulation valve is leaking
4)Turbo needs to be rebuilt

Click to expand...

1) Of course you mean bad fuel, but it sounds like he has run through some fuel.

2) Glow plugs will have zero effect.

3) Not sure what a turbo re-circulation valve is.

4) How did you come to this conclusion with such little information? If you have experience with these, it would be best to explain why you think the turbo needs to be rebuilt.

We had similar symptoms

The replaced the high pressure pump. Problem solved.