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P0128

P0128 - Coolant Thermostat Malfunction

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

Tech Notes

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

When is the code detected?

The engine coolant temperature does not reach to specified temperature even though the engine has run long enough.

P0128 Description

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

P0128 For Specific Makes

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