P0125 - Insufficient Coolant Temp for Closed Loop
Engine did not reach closed-loop temperature in expected time.
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Code Overview
Engine did not reach closed-loop temperature in expected time.
Common Causes
- Thermostat stuck open
- Low coolant level or trapped air in the cooling system
- ECT sensor reading colder than actual
- Cooling fan running too much or too early
Symptoms
- Weak cabin heat in cool weather
- Extended warm-up before closed loop
- Reduced fuel economy from staying in warm-up strategy too long
Diagnostic Steps
- Review the coolant warm-up curve from a cold start on the scan tool
- Inspect thermostat operation and housing for signs of poor sealing
- Verify coolant level and bleed air from the system if needed
- Check whether the cooling fan is running when it should not
Repair Difficulty
Moderate
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