Genuine BOSCH Glow-Duration Unit
Part number 0281003039

A glow plug relay in a car is an electrical component that plays a crucial role in the starting process of diesel engines. Its main function is to control and provide power to the glow plugs in the engine. Glow plugs are heating devices that are necessary for diesel engines to start successfully, especially in colder temperatures. The relay acts as a switch, allowing the glow plugs to warm up before the engine is started.

This relay is typically connected to the ignition switch of the car and the engine control unit (ECU). When the ignition switch is turned on, the ECU sends a signal to the glow plug relay to energize and activate the glow plugs. The relay then delivers power to the glow plugs, which heat up and begin to warm the combustion chambers in the engine. This preheating process ensures that the diesel fuel ignites properly when the engine is started, even in cold weather conditions. Once the engine is running, the relay deactivates the glow plugs as they are no longer needed for combustion.