Cylinder 4 misfire on VW — TSI coil pack failure very common; TDI injector or glow plug; older PD diesels injector loom.
Volkswagen P0304 — Cylinder 4 misfire on VW — TSI coil pack failure very common; TDI injector or glow plug; older PD diesels injector loom. Typical UK independent garage cost: £100–£580.
What actually causes P0304 on a Volkswagen
VW TSI coil packs (Bosch/Eldor) are the #1 cause of P0304 on petrol Mk5/6/7 Golfs — fail in pairs typically by 60k–80k miles. Cyl 4 (rearmost) goes first because heat is highest. On 1.6/2.0 TDI CR engines cyl 4 misfire is usually a failed injector or glow plug. Always pull plugs to check for oil/carbon before assuming coil.
Volkswagen engines that log P0304
- 1.4/1.8/2.0 TSI (Golf, Passat, Tiguan, Polo)
- 1.6/2.0 TDI CR (Golf, Passat, Caddy, Tiguan)
- 1.9 TDI PD (older Golf, Passat, Bora)
How we diagnose P0304 on a Volkswagen
- VCDS — read misfire counters per cylinder
- Swap coil 4 with coil 1, retest to confirm
- Pull spark plug — replace if worn or fouled
- On TDI, glow plug test and injector smooth-running values
- Replace component, clear codes
The common misdiagnosis to avoid
VW dealers will quote a complete coil set on a TSI with one misfire (£280+) — swap the bad cyl 4 coil with cyl 1 first, replace only what's actually failed, save the customer 70%.
Volkswagen P0304 repair cost in the UK
Expect £100–£580 including parts and labour at an independent garage. Main-dealer quotes on Volkswagen are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
On Mk5/6 Golf TSI with one failed coil, recommend doing all 4 plugs and ONLY the failed coil — the other coils will fail eventually but customer prefers an honest 'when' answer to being upsold all 4 now.
Codes usually seen alongside P0304 on Volkswagen
- P0300
- P0301
- P0302
- P0303
Symptoms drivers report with P0304
- Engine warning light flashing (not steady) under load
- Noticeable juddering at idle in gear
- Smell of unburnt fuel from the exhaust
- Misfire worse when engine is cold and damp
- Significantly reduced power
Repairs that clear P0304
- Plug & coil replacement
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0304 guide.
Reading P0304 on a Volkswagen properly
A generic reader will show P0304 and nothing else. What matters is the freeze-frame data stored with it — engine speed, load, coolant temperature and fuel trims at the moment the fault was logged — plus whether any other module on the Volkswagen has logged something at the same time. Codes rarely arrive alone, and the order they were stored in usually points at which one is the cause and which are the consequences.
Clearing P0304 without fixing it
Erasing the code resets the Volkswagen's readiness monitors as well as the light. The fault returns on the next drive cycle if the cause is still there, and in the meantime the incomplete monitors can stop the car passing an emissions check. After a genuine repair, the car is driven until the relevant monitor completes before it is handed back.
Bob's Mechanical Repairs is an independent garage in Birnam, Dunkeld, Perthshire, with 32 years of Bob's experience on the tools. If P0304 is showing on your Volkswagen, bring any scan results with you — we will read the live data ourselves, confirm which cause it actually is, and price the repair before any work starts.