OBD
P0125
Insufficient Coolant Temperature for Closed Loop Fuel Control
What it means
P0125 means Insufficient Coolant Temperature for Closed Loop Fuel Control.
Check these first
- Stuck-open thermostat
- Faulty coolant temperature sensor
- Low coolant level
- Extremely cold ambient conditions
- Fan running when it should not
What to do next
- Watch ECT warm-up time on a scan tool
- Check coolant level and bleed air from the system
- Test the thermostat opening temperature
- Verify cooling fan operation and coolant flow
- Replace the thermostat or sensor as identified
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.