Agreed. Any chance of posting the contents of the letter?New one to me. Every internal combustion engine will have carbon build up and I can't see why this is a particular issue for Audi Q5? You guys have tighter control on information manufacturer's are required to provide to consumers and Audi has been obliged to give extended warranties for issues in the USofA that they do not provide in EU. I would be interested to hear more.
I would take "cylinder head" as meaning the assembly which would include valves etc. big issue with carbon build up on fsi engines due to exhaust gas re circulation increasing carbon content by mixing carbon rich exhaust gas back into the intake manifold. I had a B7 RS4 which felt about 30-40hp down due to carbon build up.The letter specifically stated cylinder heads. No mention of intake valves. Thanks for the info. Interesting.