OBD-II code · Powertrain (generic)
P0670 Glow Plug Module Control Circuit
The control circuit between the engine controller and the glow plug control module reports a fault. The ECU can no longer reliably command the module that drives the glow plugs, so cold-start pre-heating may not run. On a diesel this causes hard starting, white smoke, and rough running until warm. Causes: open or shorted wiring between ECU and glow plug module, a failed module, or a power/ground fault at the module.
Is it safe to drive with P0670?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyGlow plug control module faulty
- PossibleWiring or connector fault
Symptoms
- Glow plug warning light on (often orange coil symbol)
- Hard cold start or no start in cold weather
- White smoke from exhaust during warm-up
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Glow Plug Module, Module Wiring
Related codes
- P0671Cylinder 1 Glow Plug Circuit
- P0672Cylinder 2 Glow Plug Circuit
- P0673Cylinder 3 Glow Plug Circuit
- P0674Cylinder 4 Glow Plug Circuit
- P0675Cylinder 5 Glow Plug Circuit
- P0676Cylinder 6 Glow Plug Circuit
- P0677Cylinder 7 Glow Plug Circuit
- P0678Cylinder 8 Glow Plug Circuit
- P066DCylinder 2 Glow Plug Control Circuit High
- P066ECylinder 3 Glow Plug Control Circuit Low
- P066FCylinder 3 Glow Plug Control Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.