My dealer just changed the water pump Yesterday.
The Q is running like a Charm. No misfiring at all ...
G Man Whats limp mode?
Are you sure your dealer didnt mess up something when they change the water pump?
Limp mode is when your car cuts power and rpm to protect itself. The computer will not allow the car to go over certain rpm or speed.
I have the same EPC lights and now the CEL. The tech told me that there's no EPC code and that it's the camshaft shift sensor - on order till next week. The EPC light started to come on after the dealer replace the water pump (steam and water from the engine).
When the EPC light is ON, the engine seems like it has a high rpm and running slow. Pulled over, turn off the car and re-start and the EPC light goes off and runs normal gain.
I'm very unlucky to have this Q5 1. transmission problem 2. waterpump 3. EPC and CEL lights
Now I'm in the market for a new SUV - not Audi of course.