P0306 on Audi
Cylinder 6 Misfire Detected
P0306 on Audi vehicles indicates cylinder 6 misfire detected. Au7o has documented this code across 4 Audi models — most commonly on A6, Q5, RS4. This code means the engine computer detected a misfire on cylinder 6 — that cylinder isn't burning its fuel-air mixture properly. The computer senses misfires by watching for tiny variations in crankshaft speed each time a cylinder should fire, and when cylinder 6 repeatedly fails to contribute, this code sets. You may feel a shake or stumble, especially at idle or under load, along with reduced power and possibly a flashing check-engine light, which signals a misfire severe enough to damage the catalytic converter. A misfire comes down to a problem with spark, fuel, or compression in that cylinder.
Common Causes of P0306
- •Worn or fouled spark plug on cylinder 6
- •Failed ignition coil for cylinder 6
- •Clogged, leaking, or failed fuel injector
- •Vacuum or intake air leak affecting that cylinder
- •Low compression (worn rings, burnt valve, head gasket)
- •Damaged plug wire or coil connector
- •Carbon buildup or worn valvetrain components
P0306 on Audi by Model
Audi A6(2 issues)
- 2019-2021 A6 3.0L Misfire Codes - Check ECM Software Before Mechanical Cleaning2019-2021
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.
- Cylinder Misfire Diagnosis and Ignition-Coil Failure — 2.7T APB/BEL2000-2004
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 Q5(1 issue)
- 2009-2025 Q5 Gasoline-Quality Deposit Diagnosis - TSB 2014753/132009-2025
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 RS4(1 issue)
- 2007-2008 RS4 Deposit-Related Cold-Start Misfire - Diagnose Before Cleaning2007-2008
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 SQ5(1 issue)
- Fuel-Quality or Deposit-Related Rough Running and Misfire Diagnosis2014-2025
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.
Looking for P0306 on a different make?
View P0306 across all makes →Frequently Asked Questions
What does P0306 mean on Audi?▼
P0306 stands for "Cylinder 6 Misfire Detected." This code means the engine computer detected a misfire on cylinder 6 — that cylinder isn't burning its fuel-air mixture properly. The computer senses misfires by watching for tiny variations in crankshaft speed each time a cylinder should fire, and when cylinder 6 repeatedly fails to contribute, this code sets. You may feel a shake or stumble, especially at idle or under load, along with reduced power and possibly a flashing check-engine light, which signals a misfire severe enough to damage the catalytic converter. A misfire comes down to a problem with spark, fuel, or compression in that cylinder. On Audi specifically, this code is documented across 4 models.
What causes P0306 on Audi vehicles?▼
Common causes on Audi: Worn or fouled spark plug on cylinder 6, Failed ignition coil for cylinder 6, Clogged, leaking, or failed fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt valve, head gasket). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0306 on a Audi?▼
Repair costs vary widely depending on the root cause and specific Audi model.
Which Audi models have P0306 documented?▼
Au7o has documented P0306 on 4 Audi models: A6, Q5, RS4, SQ5.