Cylinder 6 coil circuit fault.
P0356 — also written PO356, P 0356, 0356 — is the OBD-II code for ignition coil f primary/secondary circuit. Same code, same fix: this page covers every spelling of it.
This code means the ECU has lost control of the coil on Cylinder 6. On UK roads, we see this most often on V6 engines like the Audi 3.0 TFSI or the old Vauxhall 2.8 units where heat soak cooks the looms.
P0356 is a ignition fault code, typically costing £40–£260 to put right in a UK garage.
What P0356 actually feels like to drive
- The car feels like a bag of nails, especially under load or going up hills.
- The 'Check Engine' light is flashing at you, which usually means catalyst damage is happening.
- A heavy smell of unburnt petrol from the exhaust pipe.
- Lumpy idle that feels like the engine is trying to jump out of the mounts.
- Sudden loss of power followed by the car entering 'Limp Home' mode.
What causes P0356?
- Failed coil
- Wiring fault
UK vehicles that throw P0356 most often
- Jaguar XF 3.0 V6 (2008-2015)
- Vauxhall Insignia 2.8 V6 Turbo (A28NER)
- Audi A6 3.0 TFSI (C6/C7 platforms)
- BMW 330i/335i (N52/N54/N55 engines) 2006-2013
- Ford Mondeo 3.0 ST220 (Duratec 30)
- Land Rover Discovery 3/4 4.0 V6 Petrol
How P0356 is fixed
- Replace coil
- Repair wiring
The P0356 misdiagnosis that wastes money
I’ve lost count of how many times I’ve seen people throw six new spark plugs at a P0356, thinking it's a simple misfire. On a V6, especially those older Jaguars or Vauxhalls, the wiring harness for the rear bank (where Cylinder 6 usually lives) gets brittle from engine heat. A lot of lads swap the coil and then scratch their heads when the code comes back five miles later. Nine times out of ten, the coil's gone internal, but always check the connector pins for 'green death' corrosion before you spend a penny.
What a UK garage should charge for P0356
For a standard V6, you're looking at £50 to £80 for an initial diagnostic plug-in. A quality Bosch or Beru coil will run you between £40 and £90 depending on the motor. Labour is the kicker—on a BMW straight-six, it's a 20-minute job (£40), but on a transverse V6 where Cylinder 6 is tucked under the intake manifold, you could be looking at two hours (£120-£160). Total bill usually lands between £130 and £280 at an indie, whereas a main dealer will easily double that.
P0356 repair cost in the UK
Most P0356 repairs land between £40–£260 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 P0356
If you’re taking this to a garage, ask them to do a 'swap test' first. They should move the coil from Cylinder 6 to Cylinder 1. If the code moves to P0351, it’s definitely the coil. If it stays on P0356, you’ve got a wiring break or a fried ECU driver. Also, if your car has the Bosch individual pencil coils, don't buy the £15 eBay specials—they'll last a week and might pop your ECU. Insist on Bosch, NGK, or Delphi if you want it to pass the next MOT without the EML popping back on.
Can you drive with P0356?
Reduce load.
Urgency: high.