If you are investigating a glow-plug warning that stays on after starting, save every stored and pending code before clearing anything. Read diesel-specific codes; a basic generic reader may not access all glow-system details. Record the engine temperature and load alongside the reading; the same value can mean different things in different conditions.
A basic reader may not access every module. Check for related engine warnings and battery condition before replacing glow plugs. Use the exact vehicle’s service information to interpret the result.
Quick educational note
For information, not a diagnosis or repair instruction. Vehicle-specific checks are still required. Consult the manufacturer's guidance and a qualified technician.
How to use this information
This article explains general principles and does not establish what is wrong with your vehicle. Read the content limitations.