HotRodW

Carbon depositing is a known issue for direct injection engines. The good news is manufacturers are working on correcting the problem. The bad news is there are lots of DI engines already on the market that are prone to the build up.

HaveBullDogWillTravel

Yes...but is it not possible that poor quality fuel can cause additional crankcase vapors that need to be dealt with. Poor combustion yields more harmful vapor. Just a thought...
It's still an absolute necessity that Audi build vehicles that are designed to function properly in the countries where they are marketed.

Reggie

Yes - and the RS4 is prone more than any other vehicle. You can read the forums there on it. But Audi is not just the only mfr with the issue. All are seeing the same thing. It is not a gas issue but a result of no fuel being washed over the valves to keep them clean. With the RS if one gets a cell light then Audi (most dealers) has done the cleaning under warranty.

Marley's Ghost

Absolutely! With only one place to buy fuel, I am often amazed at the top tier discussions. Ultra Low Sulfur diesel is very rare in Mexico (Northern States and some in Guadalajara), so right now Audi is not marking clean diesel here (even though so far I have not detected sulfur coming from my exhaust.