Glow plugBelgium
Learn traffic rules with clear explanations and visual examples in our illustrated book, designed to make studying simple and engaging.
214. Glow plug
A glow plug is an electrical heating element used in diesel engines to help ignite the fuel during cold starting. It heats the combustion chamber so that the compressed air reaches conditions suitable for reliable combustion.
Modern glow plugs can continue operating briefly after the engine starts to improve combustion, reduce cold-start emissions and help the engine run smoothly while warming up.
Wikimedia.org • Chris828 • CC0
Are glow plugs checked during technical inspection in Belgium?
Glow plugs are not listed as a separate standard inspection item in the Flemish technical-inspection overview. However, diesel emissions are checked, so engine or combustion problems that cause excessive emissions can still affect the inspection result.
Can a faulty glow plug affect diesel emissions?
Yes. Poor glow plug operation can make cold combustion less effective and can contribute to increased emissions or rough running while the engine is cold.
Should a faulty glow plug be replaced?
Yes. A defective glow plug should be diagnosed and repaired according to the vehicle manufacturer's requirements, particularly when it causes difficult starting, warning messages or poor cold-engine operation.

Traffic rules
Belgium