03C121111AM serves to control the flow of the circulating coolant, which is in high flow mode if the thermostat is switched on, and low flow mode if the thermostat is switched off.
Common faults of 03C121111AM:
1.Coolant leakage occurs due to aged seal of the thermostat or other quality issues;
2.An overheated engine disables normal opening of the thermostat valve, preventing high flow of the coolant;
3.The engine temperature rises slowly and the thermostat is stuck is high flow mode. As a result, the coolant temperature is unable to rise.