Glow plugs (also known as preheat plugs) are typically replaced when they malfunction or malfunction. These can be identified by the following signs:

The preheat indicator light on the instrument panel is permanently on;
Difficulty starting in low temperatures;
Abnormal battery current draw
Replacement Recommendations
Fault Diagnosis: Use a multimeter to check the resistance value:
Infinite resistance indicates an open circuit;
Resistance close to zero indicates a short circuit

Bulk Replacement: If a single preheat plug fails, it is recommended to replace all four (usually mounted on the side of the engine) at the same time to prevent system instability caused by deterioration in the performance of other preheat plugs.

Precautions:
If a diesel engine is operated in low temperatures for extended periods, it is recommended to check the preheat system status in advance.

After replacement, test the starting performance to ensure normal battery current draw.