Coolant Temperature Below Thermostat Regulating Temperature

Thermostat stuck open. Extremely common on GM Ecotec engines. The thermostat housing is plastic and often cracks as well. Replace with an OE-quality ACDelco unit thermostat assembly (includes housing and gasket). This is practically a maintenance item on these engines -- replace every 80K miles. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.

Thermostat failure is common on the Pentastar 3.6L. The housing is integrated plastic -- replace the complete unit (Mopar). Coolant temp will struggle to reach 200F in winter. Also verify the coolant level is correct since air pockets from improper bleeding will trigger this code. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.

Thermostat sticks open around 60-80K miles. Replace with OE Wahler thermostat (Hyundai). These engines also have a known issue with the engine coolant temperature sensor giving false readings. Check sensor resistance -- most ECT sensors read roughly 2-3k ohms at 68F, but confirm the exact figure in your service manual before condemning one. Replace it if out of spec. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.

The Hemi thermostat opens at too low a temperature as it ages. Operating temp should be 203F. If the engine runs below 195F consistently, replace the thermostat (Mopar). Easy access on the Hemi -- thermostat housing is on the front of the engine near the top. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.