P0128

Description
Coolant Temperature Below Thermostat Regulating Temperature

Your engine has not reached its operating temperature in the correct time.
Symptoms
You will likely not notice any drivability problems other than the SES light.

Causes

• Low engine coolant level
• Leaking or stuck open thermostat
• Cooling fan (running too much)On all the time
• Defective coolant temperature (ECT) sensor
• Defective intake air temperature (IAT) sensor

Possible Solutions

• Replace thermostat
• Check coolant level
• Check for proper cooling fan operation (Is fan running to much)
• Replace ECT
• Check and replace (IAT) sensor if necessary.