Pharaoh126e

Hi Audi people. First I want to say how much I LOVE my new Q5. I purchased it from an awesome Audi dealership and they are very helpful....however I am having a very strage issue with it. If my Audi has sat overnight (or two nights) when I go out to start it, the brake pedal is as hard as a rock and it won't start. This only happens when it hasn't been driven for awhile. Like overnight or longer. It will always eventually start (after 2 or 3 tries) but it has happened at least 10 times now. And I always know when its going to happen because the brake pedal is hard. I brought it to the Audi dealership and of course it didn't happen because I had already been driving it. Right now they have it and I am in a loaner Q5. First thing this morning I noticed that the loaner car brake pedal was soft and it started right up. So I am not crazy but wonder if the Audi dealership might think I am. Does anybody know why this might happen?? Before the Q5 I drove an A6 and never had any problems. And my Q5 isn't a problem either, it is my favorite car just a little glitch in it. Thanks!! -Brenda

FitzLA

Sounds like an issue to me. I've had mine sit for 2-3 days at a time, even after a 10 day vacation, she started right up without hesitation. Definitely not normal.

Reggie

My RS has sat for weeks and still starts. The car should be throwing codes that the dealer should be able to diagnosis. Keeping a car overnight is fine but I am sure they will get it started on the second or third try too and will have the same codes that are throwing now.

Jusforfun

Welcome. Thanks for sharing your problem. Most likely a badly fitting hose clamp on the brake booster vacuum hose or poor diaphram seal that is allowing air to slowly leak in over time. They will have to check all components seals etc. along the system. Not familiar with the Q5 setup.
You are the first to report this problem. Its probably a hard find and a simple fix.
My guess why its not starting is; ignition override until vacuum builds... like 5 to 10 seconds So you dont drive off and fail to stop. Extra safety!
Please update us with solution when resolved.

Pharaoh126e

Thanks for the responses. I will update you if they find a problem. This morning when the dealership tried to start it, it started up. They are going to wait 2 more days and then try again. 'Justforfun' I am going to show them your post too. Thanks for your advice.

Coolieman1220

if mine sits over a week it cranks a bit then starts up with a rough idle but smoothes out right away

yob2kanobe

Is this an 09 model? My guess is the injector leak down that others have experienced. Install the updated injectors under warranty and you will be fine!

Pharaoh126e

No, it is a 2010.

HaveBullDogWillTravel

Agree...doesn't matter that it's an '09 though. I'm positive that my 2010 has at least 1 leaky injector. Every morning(especially when cold) when I start it it runs a little rough for a less than a minute and the rest of the day it AOK. I'll get dealer to check it when I get back there for something more important

pridebowl

Hi. I had the same issue about 3 times. It ended up starting after trying a bunch of times but I had the same symptoms as Pharaoh126e. But on my end it happened after a quick 10 minutes stop once, after a 2 hours stop and another time after another quick stop. Any resolution on this problem ?

Today when it happened, we heard the relay clicking when the car was supposed to start then it eventually started after removing the key, trying again (it took about 10-15 minutes). Now I'm trying to start the car and it will not fail at all... those are the worst problems, the ones you cannot reproduce !