60k miles on my audi and I am loving it but about a month or two ago I started to get some knocking noises from the dash when I first start the car and lasts a minute or two. My feeling is it has to do with Heating / AC . Both are working now but I am wondering what this could be and what this could lead to.

One other issue is my tire pressure monitoring system is malfunctioning, is there a way to determine which wheel sensor is bad or do most people just replace them all?

Thanks everyone...

 

Most likely the noise is a A/C flap motor, the Q7 has a recall for clicking motors but i haven't seen it on the A8 as much. It usually clicks for minute then stops, does that sound familiar?
As for the TPMS system, its one of the dumbest things to diagnose. Luckilly for you the A8 uses four seperate antennas instead of one like the A6 uses, so its not hard for the dealer to diagnose. You can diagnose it yourself but you need a VAG COM www.ross-tech.com which is a reversed engineered version of the dealers factory scan tool. You just have to buy the diagnostic cable.
If it were me i would just turn the TPMS system off because they are if anything.....problematic. Once it starts acting up, it always has problems.

 

Hopefully thats is, the noise does not bug me I was just concerned it was something else like a heater core.

I think I will try one fix on the TPMS at the dealer and if it goes back again just leave it off.

thanks