BMW P0301

Cylinder 1 misfire on BMW — coils and plugs first, then the well-known injector issues on N20/N54/N55.

BMW P0301 — Cylinder 1 misfire on BMW — coils and plugs first, then the well-known injector issues on N20/N54/N55. Typical UK independent garage cost: £80–£1200.

What actually causes P0301 on a BMW

N54/N55 turbocharged inline-sixes are famous for direct-injection injector failure — they leak or click open at the wrong time, causing single-cylinder misfires. BMW issued an extended warranty on these in the US (8 years/82,000 miles). On N47 diesels P0301 often pairs with swirl flap fragments or injector seal failure.

BMW engines that log P0301

• N20/N26
• N54/N55 (335i, 535i, 1M)
• N47/N57 diesel
• N52/N53 inline-six

How we diagnose P0301 on a BMW

1. Swap coil and plug from cyl 1 to cyl 2 — if misfire moves, you've found it
2. Read injector correction values per cylinder on ISTA or BimmerLink
3. On N54/N55, check injector index numbers — must match across replacements
4. On N47 diesel, inspect swirl flaps if not already deleted

The common misdiagnosis to avoid

Replacing plugs and coils on an N54 with a known injector issue is wasted money — get the injectors flow-tested or do a comparative cylinder balance test first.

BMW P0301 repair cost in the UK

Expect £80–£1200 including parts and labour at an independent garage. Main-dealer quotes on BMW 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

Always use BMW or Bosch OE plugs at the correct heat range — aftermarket NGK / Denso alternatives can run hotter and cause pre-ignition issues on direct-injection BMWs.

Codes usually seen alongside P0301 on BMW

• P0300
• P0302
• P0303
• P0304
• P00C6

Symptoms drivers report with P0301

• Engine 'juddering' like a wet dog when you try to overtake on the A9.
• The car 'kangaroos' at low speeds, especially when the engine is stone cold.
• The EML (Engine Management Light) is flashing at you—that's a 'stop now' warning for your catalytic converter.
• A distinct 'put-put-put' sound from the exhaust pipe at idle.
• Massive loss of power, feels like you're towing a caravan that isn't there.

Repairs that clear P0301

• Replace spark plug
• Swap coil pack
• Injector test
• Compression test

For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0301 guide.

Reading P0301 on a BMW properly

A generic reader will show P0301 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 BMW 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 P0301 without fixing it

Erasing the code resets the BMW'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 P0301 is showing on your BMW, 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.