Glow Plug Light (Diesel)
GarageDex's warning light guide shows the glow plug light means on a diesel engine, the glow plugs are pre-heating the cylinders for starting. Seeing it briefly when you turn the key is normal. On many diesels, a glow plug light that flashes while driving signals an engine or glow plug fault. At startup, yes: wait for it to go out, then start the engine. If it flashes while driving, get the car checked soon.
Informational - act when convenient
Looks like: A coil or spring shape.
What to do
- Turn the key to on and wait for the light to go out before cranking.
- If it flashes while driving, have the fault code read.
Common causes
- Normal pre-heating at startup
- A failed glow plug
- A glow plug relay or control module fault
How to turn it off
At startup it goes out by itself once pre-heating is done. A flashing light needs the fault diagnosed and repaired.
Frequently asked
What does the glow plug light mean?
GarageDex's warning light guide shows the glow plug light means on a diesel engine, the glow plugs are pre-heating the cylinders for starting. Seeing it briefly when you turn the key is normal. On many diesels, a glow plug light that flashes while driving signals an engine or glow plug fault. At startup, yes: wait for it to go out, then start the engine. If it flashes while driving, get the car checked soon.
Can I drive with the glow plug light on?
At startup, yes: wait for it to go out, then start the engine. If it flashes while driving, get the car checked soon.
What causes the glow plug light?
The common causes: Normal pre-heating at startup; A failed glow plug; A glow plug relay or control module fault.
How do I turn off the glow plug light?
At startup it goes out by itself once pre-heating is done. A flashing light needs the fault diagnosed and repaired.
Related guides
Other warning lights
General guidance for mainstream vehicles - your owner's manual is the authority for your car. Reviewed by the GarageDex editorial team.