P0670Glow Plug Control Module 1 Control 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
- In today's J2012 meaning P0670 is the electrical check of the activation line from the engine module to glow plug control module 1 for an open circuit; a short to ground is P0383, a short to voltage P0384, and serial communication between the modules P0683/P0684. On Bosch systems (Saab 2.2 TiD and EDC16) the engine module switches this line, detects an open load with the output off and a short to voltage with it on, and also compares the glow module's diagnostic feedback, which must switch inversely – Saab reports all line faults under P0670. GM's LB7/LLY Duramax (2004–05) used P0670 in an older meaning for glow module performance (50 of 100 samples, two trips). No current GM or Ford table uses it. If the line fails, no plug heats: hard or no cold start in frost, smoke and rough running.
- What you may notice
- Check engine light on
- Glow plug lamp behaves implausibly (stays off or on)
- Hard or no cold start in frost, since no plug heats
- Smoke and rough running after a cold start
- Likely causes
- LikelyWire or connector between engine and glow module open or corroded (bent pin, contact tension)
- PossibleGlow module faulty (input open) or without supply or ground (fuse, terminal 30)
- PossibleControl line shorted (makers reporting all line faults under P0670, e.g. Saab)
- RareOutput driver in the engine module faulty
- 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 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.