Glow plug controller fault — key diesel cold-start code.
P0670 — also written PO67O, P 0670, 0670 — is the OBD-II code for glow plug control module circuit. Same code, same fix: this page covers every spelling of it.
This isn't your plugs; it's the 'brain' that fires them up. Very common on Vauxhall and Renault diesels when the UK damp gets into the module casing or the wiring harness.
P0670 is a electrical fault code, typically costing £90–£500 to put right in a UK garage.
What P0670 actually feels like to drive
- The 'coil' pig-tail light stays on the dash longer than usual.
- 'Service Vehicle Soon' message on Vauxhalls (even though it's not due a service).
- Lumpy, smoky idle for the first 30 seconds on a frosty morning.
- No symptoms at all in summer, then won't start easily once the clocks go back.
- Battery feels like it's struggling because the pre-heat isn't helping the combustion.
What causes P0670?
- Failed glow plug module
- Wiring fault
- Failed glow plugs pulling module down
UK vehicles that throw P0670 most often
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2008-2017
- Ford Transit Custom 2.2 TDCi 2012-2016
- Renault Trafic / Vauxhall Vivaro 2.0 dCi (M9R) 2006-2014
- Mercedes-Benz Sprinter 313/316 CDI (OM651) 2009-2018
- Volkswagen Golf Mk6 1.6/2.0 TDI (CR engines) 2008-2013
- Nissan Qashqai 1.5 dCi (K9K) 2007-2013
How P0670 is fixed
- Test each glow plug resistance
- Replace glow plug module
- Replace faulty plugs
The P0670 misdiagnosis that wastes money
I see folks throwing four brand-new Bosch glow plugs at this daily, thinking 'pre-heat circuit' always means the plugs themselves. It's a waste of sixty quid and an hour of your life. On the Vauxhall 2.0 CDTi or the Transit Custom, the plugs are usually fine; it's the module's internal circuitry that’s fried or a corroded pin in the harness. If you change the plugs and P0670 stays, you’ve just ignored the brain of the system while replacing the fingers. Check the feed to the module first.
What a UK garage should charge for P0670
A decent Beru or Hitachi module will set you back £80 to £150 from a factor like Euro Car Parts or GSF. If you go to a main dealer, expect to pay £250+ just for the part. Labour is usually an hour (£60-£100 at an indie). If it's a wiring loom repair instead of a module, you're looking at more 'fiddle time' around £150. Total job usually sits around the £200 mark, unless you're at a Mercedes dealer where they'll sting you for £500 easy.
P0670 repair cost in the UK
Most P0670 repairs land between £90–£500 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 P0670
Ask the garage for a 'pin-out test' on the module connector before they order parts. You're looking for 12V supply and a solid earth. If the module isn't getting power, a new one won't fix it. Also, don't let them tell you it's an MOT failure—strictly speaking, a glow plug light isn't a fail on a diesel (unlike an SRS or ABS light), but a permanent EML/MIL light on a post-2012 car can be a 'Major' defect. Get it sorted before your test date to be safe.
Can you drive with P0670?
Yes but hard cold-start.
Urgency: medium.