Troubleshooting the Preheating System (Hyundai Elantra XD)

Malfunction	Probable causes	Method of elimination
The engine does not start at temperatures below 50°C	Poor connection in the connector or damaged wire	Repair or replace the electrical wiring
	Damage to the coolant temperature sensor	Replace the sensor
	Glow plug damage	Replace the glow plug
	Damage to the control unit of the preheating system	Check the control unit and replace it if necessary
After the first flash, the engine stops or idles unstably at temperatures below 50°C	Poor connection in the connector or damaged wire	Repair or replace the electrical wiring
	Glow plug damage	Replace the glow plug
	Glow plug relay damage	Replace the glow plug relay
	Damage to the control unit of the preheating system	Check the control unit and replace it if necessary
The yellow indicator light does not light	The light bulb burned out	Replace the lamp
	Poor connection in the connector or damaged wire	Repair or replace the electrical wiring
	Short circuit in electrical wiring	Repair or replace the electrical wiring
	Damage to the control unit of the preheating system	Check the control unit and replace it if necessary