Glow plug 1 electrical fault.
P0671 — also written PO671, P 0671, 0671 — is the OBD-II code for glow plug 1 circuit. Same code, same fix: this page covers every spelling of it.
This is a classic 'failed heater' code, usually meaning the glow plug in cylinder one has burnt out. It’s a plague on high-mileage Vauxhall CDTi and VW Group TDI engines during a UK winter.
P0671 is a electrical fault code, typically costing £30–£250 to put right in a UK garage.
What P0671 actually feels like to drive
- The engine 'coughs' or runs on three cylinders for 10 seconds after a cold morning start.
- Excessive white or grey smoke from the exhaust immediately after starting.
- 'Service Vehicle Soon' message on the dash (very common on Vauxhalls).
- Auto Start-Stop system stops working and throws a warning light.
- DPF won't regenerate because the ECU won't trigger a burn with a glow plug fault present.
What causes P0671?
- Failed glow plug (very common)
- Wiring fault
UK vehicles that throw P0671 most often
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2008-2015
- Ford Focus 1.6 TDCi (DV6) 2011-2018
- Volkswagen Golf Mk7 2.0 TDi (CRBC) 2012-2017
- Nissan Qashqai 1.5 dCi (K9K) 2007-2013
- Vauxhall Vivaro 2.0 CDTi (M9R) 2006-2014
- Audi A4 2.0 TDi (CAGA) 2008-2015
How P0671 is fixed
- Test resistance, replace faulty plug
The P0671 misdiagnosis that wastes money
I’ve seen dozens of lads buy a brand new glow plug relay or controller the second they see a P0670 or P0671 code, thinking the 'brain' has fried. It’s almost never the relay. Nine times out of ten, it’s just the heating element inside the plug itself that’s gone open-circuit. On the 1.6 TDCi Fords, I’ve also seen the wiring loom rub through against the engine lifting eye, which causes a short. Don't throw a £120 relay at it until you've spent five minutes with a multimeter testing the plug's resistance.
What a UK garage should charge for P0671
A single Bosch or NGK glow plug will set you back £15 to £25 from a local factor like Euro Car Parts. Labour is the wild card; if it comes out easy, you're looking at £40-£60. However, on an Insignia with the 'pressure sensing' plugs, the parts alone are £100+ each. A full set of four fitted usually lands between £120 and £220. Main dealers will easily double that, charging upwards of £150 per hour plus a hefty markup on the 'genuine' boxed parts.
P0671 repair cost in the UK
Most P0671 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 P0671
Here’s the golden rule: never let a garage 'just have a go' at changing these without a plan for when they snap. Ask them if they have a vibratory removal tool or a proper extraction kit. If I’m doing a set on a high-mileage Vivaro or Sportage, I’ll soak them in penetrant for three days before the job. If your garage says 'we might have to take the head off if it snaps,' find a specialist who can drill and extract them in-situ. It’ll save you a £1,500 cylinder head bill. If one has failed, the others aren't far behind—just swap the set of four.
Can you drive with P0671?
Yes but hard cold-start.
Urgency: low.