P0128 Dodge Hornet
Coolant Thermostat Below Regulating Temperature · Powertrain Code · Medium · Repair: Easy
What is P0128?
The engine coolant is not reaching the expected temperature. Most commonly caused by a stuck-open thermostat, low coolant level, or a faulty coolant temperature sensor.
When the Dodge Hornet triggers code P0128 (coolant thermostat below regulating temperature), it typically points to an issue in the powertrain system. Below you'll find the most common causes, symptoms, and repair options specific to the Dodge Hornet.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Dodge Hornet.
Common Causes on Dodge Hornet
- Thermostat stuck open on 2.0L Hurricane turbo 4-cylinder engine
- Coolant temperature sensor failure or connector corrosion
- Thermostat housing O-ring leak from thermal expansion
- Low coolant from turbo coolant line seepage
Symptoms
- Engine takes abnormally long to reach operating temperature
- Heater blows lukewarm or cold air
- Temperature gauge stays below normal or never reaches middle
- Slightly reduced fuel economy from extended open-loop operation
- Check engine light illuminated
Notes for Dodge Hornet
Hornet uses the 2.0L turbo Hurricane engine; thermostat is on the front of the block.