Code P0670 (Glow Plug Control Module Circuit) on the 6.0L Power Stroke means there is a fault in the glow plug control module circuit. This guide covers what triggers P0670, how to diagnose it, and the parts that fix it.
What P0670 means
The glow plug control module powers the glow plugs for cold starts. P0670 flags a circuit fault in that module or its wiring - not necessarily the plugs themselves.
Common causes
- Failed glow plug control module
- Wiring or connector fault to the module
- A shorted glow plug dragging the circuit
- Corroded connections
Symptoms you'll notice
- Hard cold starts and extended cranking
- White smoke and rough running on a cold start
- A glow-plug warning
- Little trouble once warm
How to diagnose it
Check the glow plug control module and its wiring/connectors. Test the individual glow plugs for a short that could be tripping the module. Confirm power and ground to the module.
The fix
Replace a failed glow plug control module, repair damaged wiring/connectors, and replace any shorted glow plug. A healthy module and set of plugs restore easy cold starting.
Frequently asked questions
Does P0670 mean bad glow plugs?
Not always - it flags the control module circuit. Test the plugs for a short, but the module and its wiring are the prime suspects.
Will P0670 stop my truck from starting?
In cold weather it can cause hard starts or a no-start; warm starts may be unaffected.
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