Common Symptoms
- Check Engine Light illuminated
- Engine takes longer than normal to reach operating temperature
- Poor fuel economy during warm-up phase
- Reduced heater performance in cold weather
- Engine may run cooler than normal on highway driving
Most Likely Root Causes
- Failed thermostat heater element
- Damaged or corroded wiring to thermostat heater circuit
- Faulty Engine Control Module (ECM)
- Short to ground in thermostat heater control circuit
- Corroded connector at electronically controlled thermostat
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Component Location
The electronically controlled thermostat is typically located at the engine coolant outlet housing where the upper radiator hose connects.
Manufacturer Notes
Electronically controlled thermostats are used on many modern engines to optimize warm-up time and improve fuel economy during cold starts.
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