Glow plug 4 electrical fault.
P0674 — also written PO674, P 0674, 0674 — is the OBD-II code for glow plug 4 circuit. Same code, same fix: this page covers every spelling of it.
This means the glow plug in cylinder number 4 (usually the one furthest from the timing belt) has bit the dust or the wiring to it is knackered. It's a classic winter headache on high-mileage Vauxhalls and VWs.
P0674 is a electrical fault code, typically costing £30–£250 to put right in a UK garage.
What P0674 actually feels like to drive
- The 'curly pig tail' warning light stays on for a bit after the engine starts.
- Lumpy, uneven idle for the first 30 seconds on a frosty morning.
- A bit of 'white' unburnt diesel smoke out the tailpipe on a cold start.
- The Stop/Start system randomly stops working (modern Fords are notorious for this).
- DPF won't regenerate because the ECU sees a glow plug fault and plays it safe.
What causes P0674?
- Failed glow plug
- Wiring fault
UK vehicles that throw P0674 most often
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2008-2015 — Very common.
- Volkswagen Golf Mk6/Mk7 2.0 TDI (CFGB/CRBC) 2009-2017.
- Ford Focus 1.6 TDCi (DV6) 2011-2015.
- BMW 320d (N47) 2007-2013 — Access is a nightmare here.
- Nissan Qashqai 1.5 dCi (K9K) 2007-2013.
How P0674 is fixed
- Replace glow plug
The P0674 misdiagnosis that wastes money
I see people throwing relays and control modules at this code every week because they’re scared of snapping a plug. They think if the 'Glow Plug Control Module' is mentioned in the scan tool, that’s the culprit. It rarely is. In my workshop, 9 times out of 10, it’s just the heating element inside the number 4 plug that’s gone open circuit. Don't go buying a £150 Hitachi module until you've done a simple continuity test on the plug itself.
What a UK garage should charge for P0674
A single Bosch or Denso glow plug will cost you £15-£25 from a factor like Euro Car Parts. Labour is the wild card. A 'quick' swap is £40-£60, but if that plug is seized solid, you're looking at specialist extraction which can hit £200. A main dealer will likely quote you £250+ just to look at it and suggest a full set. If you're in for an MOT, this won't technically fail you on emissions alone, but if it triggers the EML (Engine Management Light), it’s an automatic fail on post-2006 diesels.
P0674 repair cost in the UK
Most P0674 repairs land between £30–£250 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 P0674
If you’re taking this to a garage, ask them point-blank: "Do you use a torque-limited impact driver for removal?" If they say they just use a long breaker bar, walk away. You want a tech who knows to soak them in PlusGas for a few days first. Also, insist they check the resistance of the other three plugs while they're at it. If number 4 has died, the others are usually right behind it, and you'll save a fortune on repeat labour if you just swap the set of Bosch or NGK plugs in one go.
Can you drive with P0674?
Yes.
Urgency: low.