Cylinder 5 misfire.
P0305 — also written PO3O5, P 0305, 0305 — is the OBD-II code for cylinder 5 misfire detected. Same code, same fix: this page covers every spelling of it.
Cylinder 5 has lost its bang. Usually affects the bigger 5 or 6-cylinder lumps like the Volvo T5s or BMW straight-sixes common on UK roads.
P0305 is a ignition fault code, typically costing £30–£800 to put right in a UK garage.
What P0305 actually feels like to drive
- Engine feels 'lumpy' or shakes like a wet dog when idling at the lights.
- The car 'kangaroos' or hesitates when you try to overtake on the A9.
- A heavy smell of unburnt petrol from the exhaust pipe.
- Check Engine light flashing rapidly when you put the engine under load.
- Fuel economy has absolutely tanked—getting 20mpg when you usually get 40.
What causes P0305?
- Spark plug
- Coil
UK vehicles that throw P0305 most often
- Volvo V70/S60 2.4/2.5 T5 (All years)
- BMW 330i/335i (E90/E92) N52/N53/N54 engines 2006-2012
- Land Rover Discovery 3/4 2.7 TDV6 (Cylinder 5 injector failure) 2004-2015
- Audi A4/A6 2.4/3.0 V6 2004-2011
- Ford Focus ST225 (2.5 5-pot Duratec) 2005-2011
- Mercedes-E280/E320 (W211) V6 M112 engines
How P0305 is fixed
- Plug & coil replacement
The P0305 misdiagnosis that wastes money
I’ve lost count of how many times I’ve seen folks chuck a set of cheap eBay coils at a P0305, only to find the light stays on. On the BMW N53 or N54 engines, people ignore the injectors, but it's often a leaky piezo injector soaking the plug. On the big Volvo T5s, I’ve seen guys swap everything only to realise the wiring loom to No. 5 has chafed through near the lift eye. Don't just assume it's the 'sparky bits' because the code says misfire.
What a UK garage should charge for P0305
A single NGK spark plug and a Delphi coil pack for a Focus ST will set you back about £70-£90 including VAT from a local factor. Labour is usually an hour (£60-£100). However, if it's a BMW N54 injector, you're looking at £350 per injector plus coding. A basic plug swap on an old V6 Merc might only be £40. Main dealers will easily double these prices, charging £180 just to plug in their 'official' computer.
P0305 repair cost in the UK
Most P0305 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 P0305
Before you let a garage sell you a £300 set of Bosch coils, ask them to do a 'swap-test'. Move the No. 5 coil to No. 1 and the No. 5 plug to No. 2. If the code moves to P0301, it’s the coil; if it goes to P0302, it’s the plug. If P0305 stays put, you're looking at an injector or, worse, a compression issue. If they won't do this 10-minute test and just want to 'parts-cannon' it, take your keys and run. A proper diagnostic fee (£50-£80) saves you hundreds in the long run.
Can you drive with P0305?
Drive gently.
Urgency: high.