Glow Plug / Wait to Start (Diesel)

On diesel engines, glow plugs preheat the combustion chamber for cold starts. The light illuminates briefly at startup while glow plugs warm up — wait for it to go off before cranking. If it stays on, a glow plug has failed.

1. 1Normal at startup: wait for the light to go out (usually 2–10 seconds), then start the engine
2. 2If light stays on permanently: one or more glow plugs have likely failed
3. 3Failed glow plugs cause hard cold starts and rough idle when cold
4. 4Glow plug replacement: $20–$50 per plug — typically all are replaced at once

If your scanner returns one of these codes, use MyOBDCode to decode it for full repair cost estimates.