OBD-II code · Powertrain (generic)
P066B Cylinder 1 Glow Plug Control Circuit High
The control line for the glow plug on cylinder 1 is open or shorted to supply - the plug cannot be heated.
Is it safe to drive with P066B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen in plug or wiring
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
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
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.4–1.4 h
- Emissions test
- Likely to fail
- Parts involved
- Glow Plug Cyl 1, Glow Plug Wiring Cyl 1
Related codes
- P066DCylinder 2 Glow Plug Control Circuit High
- P066FCylinder 3 Glow Plug Control Circuit High
- P067BCylinder 4 Glow Plug Control Circuit High
- P067DCylinder 5 Glow Plug Control Circuit High
- P067FCylinder 6 Glow Plug Control Circuit High
- P068DCylinder 7 Glow Plug Control Circuit High
- P068FCylinder 8 Glow Plug Control Circuit High
- P069BCylinder 9 Glow Plug Control Circuit High
- P069DCylinder 10 Glow Plug Control Circuit High
- P06E1Cylinder 11 Glow Plug Control Circuit High
- P06E3Cylinder 12 Glow Plug Control Circuit High
- P0668Control Module Internal Temperature Sensor A Circuit Low
- P0669Control Module Internal Temperature Sensor A Circuit High
- P066ACylinder 1 Glow Plug Control Circuit Low
- P066CCylinder 2 Glow Plug Control Circuit Low
- P066ECylinder 3 Glow Plug Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.