Diesel Trouble Codes

P0670 — Glow Plug Control Module Circuit (6.7 Power Stroke)

P0670 on the 6.7 Powerstroke means the PCM has detected a fault in the glow-plug control module circuit. Affected systems are glow plugs and cold start.…

Updated September 1, 2026

What it means

The PCM has detected a fault in the glow-plug control module circuit. Affected systems: glow plugs, cold start.1

Most likely causes

  1. Glow-plug control module failure — Module internal fault or loss of communication with PCM.1
  2. Wiring/harness damage to control module circuit — Chafed, corroded, or open wiring between PCM and glow-plug control module.1
  3. Individual glow plug or its circuit fault — Open/short in a glow plug or its feed can trigger module circuit DTC on this platform.1

How to diagnose

  1. Verify code and freeze frame; confirm cold-start symptom present.
  2. Inspect glow-plug control module connectors for corrosion/moisture; check harness routing for chafe points.
  3. Check module power/ground and communication circuits per wiring diagram; look for opens/shorts.
  4. Perform module self-test/functional check with scan tool if supported; monitor glow-plug activation data during cold start.
  5. Isolate glow-plug circuits; test resistance/continuity of each glow plug and its wiring to module.
  6. Clear codes and retest after repairs; confirm no recurrence on cold start.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by market and extent of wiring damage; obtain a local estimate.

When to see a pro

Glow-plug control circuits are high-current and tied to engine control. If diagnosis points to internal module failure, harness damage, or in-cylinder issues, have a qualified diesel technician perform testing and repairs. Do not attempt high-pressure fuel or safety-critical repairs without proper training and equipment.

Sources

  1. Curated DTC seed — 6.7 Powerstroke (curated) ↩︎ ↩︎ ↩︎ ↩︎

Watch a repair

Third-party videos, not ours — for illustration. Confirm anything against the factory service information for your truck.

How to Replace Glow Plug Control Module 2008-2010 Ford F-250 — TRQ