Glow Plug Light (Diesel): what it means and what to do
Color: Amber/yellow (coil symbol)
Urgency: Normal briefly at startup. Flashing while driving = fault.
What it means
On diesel engines it shows the glow plugs are preheating. Flashing usually indicates an engine or glow plug fault.
Is it safe to drive?
Wait for it to go out before cranking. If it flashes while driving, get it checked soon.
Likely causes
- Normal preheat cycle
- Failed glow plug
- Glow plug relay/controller
- Engine sensor fault
Typical cost ranges
Rough general estimates for US shops (parts and labor). Your price depends on vehicle, region, and shop.
| Repair | Rough range |
|---|---|
| Glow plug | $150–$800 for a set installed (varies widely) |
| Glow plug controller | $150–$500 |
What to tell the shop
Note hard starting in cold weather, white smoke, and whether the light flashes; ask for codes.
Frequently asked questions
What does the Glow Plug Light mean?
On diesel engines it shows the glow plugs are preheating. Flashing usually indicates an engine or glow plug fault.
Is it safe to drive with the Glow Plug Light on?
Wait for it to go out before cranking. If it flashes while driving, get it checked soon.
What causes the Glow Plug Light to come on?
Common causes include: Normal preheat cycle; Failed glow plug; Glow plug relay/controller; Engine sensor fault.
How much does it cost to fix the Glow Plug Light problem?
Rough general estimates: Glow plug: $150–$800 for a set installed (varies widely); Glow plug controller: $150–$500. Actual costs vary by vehicle, region, and shop.
What should I tell the mechanic?
Note hard starting in cold weather, white smoke, and whether the light flashes; ask for codes.
General information only, not professional mechanical advice. Check your owner's manual, and if in doubt, stop safely and call for help.