P0304 on Audi

Audi states that contaminated gasoline or gasoline with insufficient deposit-control additives can contribute to deposits on intake valves, the intake manifold, fuel injectors and combustion chambers. Possible results include rough running after cold start, extended cranking, hesitation, rough idle, reduced performance, poor fuel economy or an MIL with supported misfire, lean-system or cylinder-imbalance faults. This does not establish a universal A4 2.0T intake-valve defect, mandatory walnut-blasting interval or fixed failure mileage.

Audi TSB 2033561/2 applies only to CAEB-engine A4/A4 Avant vehicles in these VIN-suffix ranges: 2010 AA121937-AA999999 or AN045790-AN999999; 2011 BA000001-BA128744 or BN000001-BN045180. The supported condition is an engine that shakes with P0300, P0301-P0304 and/or P130A because certain installed Bosch coils may fail prematurely. The bulletin does not establish a 2009-2021 A4-wide failure or a preventive replacement interval.

For a 2019-2021 Audi A6 equipped with the 3.0L TFSI engine, the malfunction indicator lamp may illuminate with P0300 and one or more cylinder-specific P0301-P0306 codes. Audi's service information identifies an applicable ECM software-calibration condition and publishes model-year-specific software levels. Misfire codes alone do not prove intake-valve carbon buildup, and the previous card incorrectly grouped 2011-2023 A6 models, multiple unrelated engine generations, a fixed walnut-blasting interval, fuel additives, universal catch cans, and generic shopping searches into one diagnosis. This corrected record covers only the Audi-documented software condition; carbon cleaning or parts replacement requires separate physical diagnosis if the misfire remains after the software level and other common causes are checked.

A rough-running 2000-2004 A6 2.7T with P0300-P0306 has a detected misfire, but those faults do not prove that an ignition coil is defective. Audi TSB 2023120/2 says that campaign-era Generation II coils generally should not be assumed to be the root cause. Engine code also changes the coil: APB applications use 058905105, while BEL applications use 06A905115D. The former record incorrectly cited headlight-wiring recall 04V-133 as an ignition-coil recall and encouraged replacing a full set without diagnosis.

Audi states that contaminated gasoline or gasoline with insufficient deposit-control additives can contribute to deposits on intake valves, the intake manifold, fuel injectors and combustion chambers. Possible results include rough running after cold start, extended cranking, hesitation, rough idle, reduced performance, poor fuel economy or an MIL with misfire, lean-system or air/fuel-ratio-imbalance faults. This does not establish a universal Q5 intake-valve defect, a mandatory walnut-blasting interval or a fixed failure mileage.

Audi guidance documents that fuel-related deposits can cause a rough cold start, hesitation, reduced performance and misfire faults. For the B7 RS4 4.2L FSI V8, Audi TSB 2022030/2 treats P0300 and cylinder-misfire faults as a diagnostic starting point and first distinguishes injector deposits from other causes. These symptoms do not by themselves prove intake-valve buildup, and Audi does not specify a recurring 30,000-60,000-mile cleaning interval in the cited guidance.

Audi states that contaminated gasoline or gasoline with insufficient deposit-control additives can contribute to deposits in injectors, combustion chambers, the intake manifold and intake valves, with rough running, hesitation, reduced performance, poor fuel economy or related ECM faults. This does not establish a universal SQ5 intake-valve defect, a mandatory walnut-blasting interval or a fixed mileage. Audi separately warns that unapproved fuel additives are not permitted on 2018-2025 EA839 V6 TFSI SQ5 models because a negative effect on engine life cannot be ruled out.