AUDI Q7/ 2008 it just cant be repared [Archive] - Audi Forums

: AUDI Q7/ 2008 it just cant be repared

07-24-2019, 11:46 AM
Hi forum, about a year ago I satarted to have issues with my audi q7 2008, it was loosing power on drive and over drive and this just was impossible to drive, i took it to the shop ( not Audi dealer ) and the mechanic read probles on the fuel pressure 1 and 2 as well as the lambda sensor. They all were replaced for new Audi original parts but it wasnt fixed and the mechanic told me he just couldnt do it and he couldnt figure it out, then another mechanic challenged that same issue and fe couldt do anything but told me that the problem was on the whole transmission and transfer, that i had to replace them all and my probles would dissapear. Then out of the nothing the car starts to response like new!! for 2 days and then the erros came back, then randomly the Q7 would start and work fine but then in a split of a second this would fail again. Then i opted to restart the engine in a very non ortodox way, i would just off and on in a fraction of a second and then i´d be happy for maybe 10 minutes and then would go erratic again. Now its so hard to get that lucky and start the engine and make the car work fine. I purchased my own scanner just to see live what was going on before the service engine sign would flash again.
Im dissapointed and taking it to the dealer would be just way way more expenive. Here in Mexico a diagnose at the dealer goes for 300 US dollar up and my car its a 2008 so I feel it can be repaired externally before swapping parts as the other mechanics did and delivered the same car. So far the parts i got for new the old ones where just fine and had no defects but the lambda sensor which was really damaged. If my car does random good runs whats wrong with it? I dont want to get rid of it because it was a gift from a dearest person that just passed away. I want to keep it but working just fine. If somebody knows the answer id appreciate it.

07-30-2019, 07:38 PM
I suggest looking for a corroded or loose ground connection.

Don’t know if this is your issue - but it certainly sounds all too familiar even considering it was on an A-4 and not a Q-7. What seems so familiar is the intermittent loss of power, various different indicated failures.

My experience with this issue was frustrating, somewhat expensive and time consuming to resolve - but in the end it was a simple and inexpensive final fix. Hopefully yours is resolved quickly.

My experiences:
We fought a similar issue with a 2007 A-4. For multiple years we had intermittent issues where the car lost power for no apparent reason. It would still run and we could still drive it - but it was less than a limp mode - or so it seemed.

Sometimes shutting the car down, waiting a few minutes and restarting it would seem to solve the issue. Diagnosis came back with a variety of issues - each instance indicated a different cause when the computer decided to drop a code :( - although the same symptoms.

The technicians spent MANY hours on the phone with Audi’s tech support - but it never really helped very much.

We ended up replacing multiple sensors, valves etc. with the most significant replacement being an entire wiring harness. Each repair would seem to resolve the issue - at first - but it would then reoccur. Ultimately we found the true root cause - a corroded ground connection to the chassis. It was in an obscure connection - but we finally found the corroded connection. Cleaned and reset the connection - issue resolved - no issues since.

08-07-2019, 08:27 PM
Sounds exactly to what happens to me. Do you remember where on your car was that corroded ground? It may be in a very similar place thy being on a different Audi model
I was about to un mount the seat to check on the batterie’ s grounds , but if it happens to be on another usual grounding area for Audi Q7 it’ll be awesome to know .
I did replace many “ good working sensors” and many other parts that were wrongfully replaced and still giving me bad codes and lucky starts randomly