P0671
Cylinder 1 Glow Plug Circuit
Moderate· Fix soonIntermediatePowertrainGeneric, all makes
What it means
The glow plug for cylinder 1 on this diesel engine is not drawing the expected current, so it is probably burned out or its wire is broken.
Is it safe to drive?
Safe to drive once started. Cold starts will be harder and you may see white smoke until the engine warms up.
Symptoms
- Check engine or glow plug light on
- Hard starting in cold weather
- White smoke and rough running after a cold start
Probable causes
Most likely first
- 1Burned-out glow plug
- 2Failed glow plug control module or relay
- 3Damaged wiring or loose terminal nut
- 4Blown glow plug fuse
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Measure glow plug resistance; most read under 2 Ω, and an open circuit means the plug has failed.
- 3Check that the glow plug module supplies voltage when the key is turned on cold.
- 4Inspect the wiring and terminal nuts on top of the plugs.
- 5Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Replace the glow plug(s). Use penetrating oil and care: seized plugs can snap in the head
- Replace the glow plug module or relay
- Repair the wiring
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.