P0671Cylinder 1 Glow Plug Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Modern diesel glow systems switch each glow plug through its own power semiconductor (in a glow plug module or the engine module), so current and faults can be measured per plug; a faulty channel is switched off. CARB requires glow plugs to be checked for correct current and voltage drop and, since model year 2010, a single plug outside specification to be detected and named. P0671 means the load circuit of the cylinder 1 glow plug is open while glowing. Thresholds: GM engine-module drivers 200 kΩ or more (two trips), GM's L5P glow module less than 4.0 A at over 6 V, Ford's 2023 Power Stroke less than 1 A for about 1 s. Older GM systems (LB7/LLY, LML) report open and short under this one code. Chrysler advises checking the main B+ feed and ground of the glow module first when several cylinder codes appear together.
- What you may notice
- Check engine light (GM also glow plug lamp)
- Harder cold start in low temperatures
- Rough idle, knocking and white or blue smoke after a cold start
- Often no symptoms when warm
- Likely causes
- LikelyGlow plug cylinder 1 burnt out (element open)
- PossiblePlug connector loose or corroded, terminal nut loose, wire broken
- PossibleGlow module supply or ground (several cylinder codes at once)
- RareGlow module or driver faulty, or software (GM 3.0 L 2020)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.