Urgency: Low
Glow Plug Light (Diesel)
This is usually informational. Address it at your convenience.
What the Glow Plug Light (Diesel) Means
On a diesel your car, the coiled glow-plug light is normal at start-up: it shows the glow plugs are pre-heating the cylinders. You wait for it to go out before cranking. If it flashes after warm-up, it signals a glow-plug or engine management fault.
Common Causes
- Normal pre-heat cycle (steady, brief)
- One or more failed glow plugs
- Glow plug relay fault
- Crankshaft/camshaft sensor issue
- Related engine management fault
How to Fix It
- At cold start, wait for the light to go out before cranking
- If it flashes, scan for glow-plug and engine codes
- Test each glow plug for resistance/continuity
- Replace failed plugs (ideally as a set) and check the relay
- Clear codes and confirm easy cold starts
Related DTC Codes
| Code | Meaning |
|---|---|
P0335 | Crankshaft Position Sensor Circuit The crankshaft position sensor signal is faulty, which can cause stalling or a no-start condition. |