Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- Insufficient warm up time - Low engine coolant level - Leaking or stuck open thermostat - Engine coolant temperature sensor harness is open or shorted - Engine coolant temperature sensor circuit poor electrical connection - Faulty engine coolant temperature sensor

When Detected

Coolant temperature does not reach predicted engine coolant temperature within specific time

Tech Notes

If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.

Description

Indicates that the thermostat monitor has not achieved the required engine operating temperature within a specified amount of time after starting the engine.