P0308 on Audi
Cylinder 8 Misfire Detected
P0308 on Audi vehicles indicates cylinder 8 misfire detected. Au7o has documented this code across 2 Audi models — most commonly on RS4, S7. P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. Typical repair costs on Audi range from $800 to $2,000, depending on the specific model and root cause.
Common Causes of P0308
- •Worn, fouled, or incorrectly gapped spark plug on cylinder 8
- •Failed ignition coil or coil-on-plug for cylinder 8
- •Faulty, clogged, or leaking fuel injector
- •Vacuum or intake air leak affecting that cylinder
- •Low compression (worn rings, burnt/leaking valve, head gasket)
- •Damaged spark plug wire or boot (on applicable engines)
- •Carbon buildup or sticking valve
P0308 on Audi by Model
Audi RS4(1 issue)
- 4.2L V8 Carbon Buildup on Intake Valves2007-2008
The B7 Audi RS4 with the high-revving 4.2L FSI V8 develops significant carbon deposits on the intake valves due to direct fuel injection. This high-performance engine is particularly affected because of its FSI system design.
Audi S7(1 issue)
- Carbon Buildup on Intake Valves (4.0T Twin-Turbo V8)2012-2018
The Audi S7 (2012-2018) with the 4.0T twin-turbo V8 develops carbon buildup on intake valves due to direct fuel injection. With 8 cylinders and twin turbochargers generating high crankcase pressure, carbon accumulation is more aggressive than on smaller engines. The hot-vee design (turbochargers mounted between the cylinder banks) also contributes to higher under-hood temperatures that bake deposits faster. Symptoms appear between 40,000-80,000 miles and include rough idle, misfires, and reduced power. Walnut blasting on a V8 is more expensive than on 4-cylinder engines due to double the cylinders and the complexity of the hot-vee layout. Audizine and AudiWorld forums recommend cleaning every 40,000-60,000 miles as preventive maintenance. Neglecting carbon cleaning can lead to valve damage and $6,000+ engine repairs.
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View P0308 across all makes →Frequently Asked Questions
What does P0308 mean on Audi?▼
P0308 stands for "Cylinder 8 Misfire Detected." P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. On Audi specifically, this code is documented across 2 models.
What causes P0308 on Audi vehicles?▼
Common causes on Audi: Worn, fouled, or incorrectly gapped spark plug on cylinder 8, Failed ignition coil or coil-on-plug for cylinder 8, Faulty, clogged, or leaking fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0308 on a Audi?▼
Repair costs on Audi range from $800 to $2,000, depending on the specific model and root cause.
Which Audi models have P0308 documented?▼
Au7o has documented P0308 on 2 Audi models: RS4, S7.