What are the symptoms of P0670?

Common symptoms include: Hard cold starts; Rough cold running; Check-engine light.

What causes a P0670 code?

The most common causes are: Failed glow plug control module (GPCM); Wiring between ECM and module; Power/ground fault.

How do you fix P0670?

Check module power, ground, and control signal; Inspect wiring/connectors; Replace the glow plug module if faulty. Worth diagnosing soon — left alone, the underlying issue can grow into a bigger, costlier problem.

OBD-II Code Lookup

P0670Watch

Glow Plug Module Control Circuit

Cold Start system

The glow-plug control module circuit is faulty — the module that powers and times the glow plugs isn't communicating or operating correctly.

Worth diagnosing soon — left alone, the underlying issue can grow into a bigger, costlier problem.

Common symptoms

Hard cold starts
Rough cold running
Check-engine light

Common causes

Failed glow plug control module (GPCM)
Wiring between ECM and module
Power/ground fault

How it's diagnosed & fixed

Check module power, ground, and control signal
Inspect wiring/connectors
Replace the glow plug module if faulty

Got P0670? Get it diagnosed.

A real technician can interpret P0670 in the context of your truck and symptoms — and tell you what's actually wrong before you buy parts.

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Related Cold Start codes

P0380Glow Plug/Heater Circuit 'A' Malfunction P0540Intake Air Heater Circuit P0683Glow Plug Module to ECM Communication Circuit

Reference only. A trouble code names a symptom, not the failed part — always confirm with a live diagnosis before repairs. See our Knowledge Base for deeper guides.