The glow plug light, also known as the preheat light, is an indicator on a diesel engine that tells the driver that the engine’s glow plugs are heating up. These plugs are used to heat the air in the combustion chamber before the engine is started, making it easier to start the engine in cold weather.
If the glow plug light is flashing, it usually indicates a problem with the engine’s glow plug system. Some common causes of a flashing glow plug light include:
- Failed glow plugs: Over time, the glow plugs in a diesel engine can wear out and fail. If one or more of the plugs is not working properly, the light will flash to alert the driver.
- Faulty relay: The glow plug relay is responsible for controlling the power to the glow plugs. If the relay is faulty, the light will flash.
- Wiring issues: The wiring that connects the glow plugs to the rest of the engine’s electrical system can become damaged over time. If this happens, the light will flash.
- Control module: The engine control module may be responsible for controlling the power to the glow plugs. If the module is faulty, the light will flash.
If the light is flashing, it’s important to have the vehicle inspected by a qualified mechanic as soon as possible. A flashing glow plug light can lead to engine damage if not addressed in a timely manner. Ignoring the warning can lead to increased emissions, reduced fuel economy and potential engine damage.
In order to diagnose the cause of a flashing glow plug light, a mechanic will use an OBD (on-board diagnostics) device. An OBD device is a tool that can be plugged into the vehicle’s diagnostic port to read and clear diagnostic trouble codes (DTCs) stored in the engine control module (ECM).
To use an OBD device to diagnose the cause of a flashing glow plug light, the mechanic will first connect the device to the vehicle’s diagnostic port. The device will then read the DTCs stored in the ECM, which will provide information about the specific problem with the glow plug system.
Once the DTCs have been read, the mechanic can use the information provided by the OBD device to diagnose the problem and make any necessary repairs. For example, if the DTCs indicate that a specific glow plug is not working properly, the mechanic will replace that glow plug.
In summary, a flashing glow plug light on a diesel engine is a warning sign of a potential problem with the engine’s glow plug system. Common causes include failed glow plugs, a faulty relay, wiring issues, or a faulty control module. It is important to have the vehicle inspected by a qualified mechanic as soon as possible to avoid potential engine damage.