Audi A6 Fuel System Failure Causing Multiple Issues

Had nearly identical symptoms on my A4 (2012, 2.0T). The rough idle, excessive fuel consumption, and hard starts pointed to clogged fuel injectors, which was causing engine misfires and poor emissions. The repair involved removing and professionally cleaning all injectors, plus replacing two that were beyond salvage. The carbon buildup was severe, clearly visible when the injectors were pulled. The repair also included new seals and gaskets since everything was already apart. This was a serious issue that needed immediate attention, as continued driving risked damaging the catalytic converter and oxygen sensors. After the repair, fuel economy improved significantly, idle smoothed out, and cold starts became normal again. Key signs it was injection-related: Rough, unstable idle, Higher than normal fuel consumption, Hesitation during acceleration, Check engine light with misfire codes Would strongly recommend finding a shop that specializes in Audi fuel systems, as proper diagnosis and repair requires specific knowledge and equipment.

Since it was all injection related I made the exact same experience with my A6 back then. The misfire caused by the faulty injectors got worse over time and the engine would really struggle, especially during cold starts. Finally got it fixed at a specialized diesel shop, they cleaned the entire system and replaced two injectors. Did you end up fixing yours and remember roughly how much it cost? Also curious if any other issues popped up afterward since these injection problems sometimes trigger a chain reaction.

After getting it properly diagnosed, the faulty injection system was indeed the root cause. The mechanic found one completely defective nozzle that needed replacement, plus heavy deposits in the others causing the poor engine performance and excessive gasoline consumption. The repair cost came to 515 Euro total, which included cleaning the entire fuel injection system, replacing the defective injector, and testing everything afterward. Since fixing it 6 months ago, the vehicle runs perfectly, no more misfires, rough idle is gone, and fuel economy is back to normal. No secondary issues have emerged since the repair. The engine starts reliably even on cold mornings, and performance is smooth across all RPM ranges. Looking back, addressing the injection problem early prevented potential damage to other components. My advice would be to get injection issues fixed promptly, as running with faulty injectors can lead to more serious engine damage over time.

Thanks to everyone who responded. After getting lots of great advice here, I bit the bullet and took my A6 to a specialized fuel injection shop last week. The diagnosis confirmed what many suggested, severe injector issues were causing the misfire problems. They found two completely clogged injectors that were destroying my fuel economy and engine performance. The repair involved a full system cleaning plus replacing those two bad injectors. Total cost came to 680 Euro, which included parts and labor. The vehicle runs like new now, no more rough idle, cold starts are perfect, and my fuel consumption is back to normal. Really glad I got it sorted before any permanent engine damage occurred. The shop did great work and actually showed me the gunked-up old injectors. Made it clear why the gasoline consumption was so terrible before. If anyone else faces similar symptoms, definitely get it checked sooner rather than later.