Cylinder 8 misfire.
P0308 — also written PO3O8, P 0308, 0308 — is the OBD-II code for cylinder 8 misfire detected. Same code, same fix: this page covers every spelling of it.
This is a misfire on the cylinder tucked way at the back of a V8 engine, usually found on big Jags, Range Rovers, or older BMWs. In my experience, it's almost always heat-related because that back corner gets roasting.
P0308 is a ignition fault code, typically costing £40–£900 to put right in a UK garage.
What P0308 actually feels like to drive
- The car feels like it's 'shuddering' when you're pulling away from a roundabout.
- A distinct 'ticking' or 'chugging' sound from the back of the engine bay at idle.
- The 'Check Engine' light is flashing orange, usually when you're trying to overtake on the motorway.
- Strong smell of unburnt petrol coming from the exhaust pipe.
- The stop-start system has completely disabled itself and flagged a 'System Fault'.
What causes P0308?
- Spark plug
- Coil
UK vehicles that throw P0308 most often
- Range Rover Sport 4.2 / 5.0 V8 (L320/L494) 2005-2018
- Jaguar XF / XJ 4.2 & 5.0 V8 (X250/X351) 2008-2015
- BMW 5 Series 545i / 550i (E60/F10) 2003-2016
- Land Rover Discovery 4 5.0 V8 2009-2013
- Mercedes-Benz E500 / E63 AMG (W211/W212) 2002-2016
How P0308 is fixed
- Plug & coil replacement
The P0308 misdiagnosis that wastes money
I see it all the time on the Range Rovers—people see a misfire and immediately bin a perfectly good coil pack or a set of Iridium plugs. On these big V8s, P0308 is often actually a vacuum leak right at the back of the manifold or, worse, a failing fuel injector. Because cylinder 8 is tucked right up against the bulkhead where it gets the most heat and the least airflow, the wiring looms get brittle. I’ve seen lads spend £400 on ignition bits when it was just a £5 cracked breather pipe or a crusty connector pin.
What a UK garage should charge for P0308
For a basic plug and coil swap on a BMW or Jag, you're looking at about £120 to £180 using Bosch or Delphi parts. However, if the injector has gone south, you're looking at £450 upwards because of the labour to get the fuel rail off. A main dealer will likely quote you £900+ for a full set of plugs and coils just to cover their backs. Most independent garages like mine will charge a £50-£70 diagnostic fee to plug the Snap-On tool in and confirm exactly what's dropping out.
P0308 repair cost in the UK
Most P0308 repairs land between £40–£900 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 P0308
If you’re taking it to a garage, ask them to do a 'cylinder drop test' and a compression check specifically on the rear bank before they start fitting parts. If it’s a Jag or a Range Rover, insist they swap the coil from cylinder 8 to cylinder 2 to see if the code 'follows' the coil—it’s a five-minute job. If the code stays on P0308, you've just saved yourself buying a coil you didn't need. Also, check your oil level; these modern VVT systems hate being low on oil and it can cause timing-related misfires that look like ignition issues.
Can you drive with P0308?
Drive gently.
Urgency: high.