Cylinder 1 isn't firing properly.
P0301 — also written PO3O1, P 0301, 0301 — is the OBD-II code for cylinder 1 misfire detected. Same code, same fix: this page covers every spelling of it.
Basically, No. 1 cylinder (the one closest to the timing belt) isn't pulling its weight. It's a proper common sight on the Vauxhall 1.2/1.4 petrols and the Ford EcoBoost engines.
P0301 is a ignition fault code, typically costing £30–£800 to put right in a UK garage.
What P0301 actually feels like to drive
- 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.
What causes P0301?
- Spark plug worn
- Coil pack failed
- Injector fault
- Compression loss
UK vehicles that throw P0301 most often
- Vauxhall Corsa D/E 1.2 & 1.4 (A12XER/A14XER) 2010-2018
- Ford Focus/Fiesta 1.0 EcoBoost (M1DA/SFJA) 2012-2020
- VW Golf Mk7 1.4 TSI (CHPA/CZDA) 2013-2017
- BMW 3 Series (N43/N53 engines) 2007-2013
- Vauxhall Insignia 2.0 CDTi (A20DTH) - Injector wiring issues
- Peugeot 208/308 1.2 PureTech (EB2) 2014-present
How P0301 is fixed
- Replace spark plug
- Swap coil pack
- Injector test
- Compression test
The P0301 misdiagnosis that wastes money
I see too many folks rushing to Euro Car Parts for a cheap ignition coil at the first sign of a P0301. On the 1.0 EcoBoost Fords, I’ve had lads swap coils and plugs three times only to find the real culprit is a tiny coolant leak from the degas hose dripping onto the plug, or worse, a burnt valve. Don't just throw a Delphi coil at it and hope; if it's a diesel, it's rarely the glow plug causing a 'misfire' code while driving—that's usually a tired Denso injector or a gummed-up EGR valve.
What a UK garage should charge for P0301
A simple NGK spark plug swap might only set you back £50 including 20 mins labour. If it’s a failed coil pack on a Corsa, you’re looking at £120-£160 for a decent Bosch unit. However, if I have to pull an injector out of a Transit or an Audi, you’re looking at £250-£400. If we do a compression test and find a dead cylinder, you’re into 'top-end rebuild' territory, which is £800 plus VAT. Main dealers will often double these prices just for the fancy coffee in the waiting room.
P0301 repair cost in the UK
Most P0301 repairs land between £30–£800 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0301
Before you let a garage sell you a £300 set of injectors, ask them to 'do a swap-test.' It’s the oldest trick in my book. If P0301 is showing, I’ll move the No.1 coil to No.2. If the code moves to P0302, you know it’s the coil. If it stays on No.1, it’s a plug, injector, or a mechanical headache. If they won't do that five-minute test and just want to 'parts-cannon' it, find another workshop. Also, insist on NGK or Bosch plugs; I've seen cheap 'no-name' plugs snap in the head, and that’s a £1,000 bad day.
Can you drive with P0301?
Drive gently — risk to cat.
Urgency: high.