P0125: Insufficient coolant temp for closed loop fuel control
Drive carefully. Get it checked within a week or two.
Can I drive with P0125?
Yes, but drive carefully and get it checked soon. The engine takes too long to warm up, wasting fuel and increasing tailpipe emissions.
What does P0125 mean?
P0125 stands for Insufficient Coolant Temperature for Closed Loop Fuel Control.
Symptoms you may notice
- Cabin heater blows lukewarm or cool air in cold weather
- Dashboard temperature gauge stays near cold or fluctuates
- Radiator cooling fans running at high speed continuously
- Decreased gas mileage due to prolonged engine warm-up
How much does it cost to fix?
Repair costs for code P0125 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:
- Engine thermostat stuck open
- Faulty engine coolant temperature sensor
- Low coolant level leaving sensor dry
- Cooling fan running continuously
What to do next
- Check engine coolant level in the radiator and reservoir.
- Monitor coolant temperature during highway driving to see if it reaches 180°F-200°F.
- Replace the engine thermostat if cabin heater blows lukewarm air.
Last updated: October 2026
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General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.
About this code
Code P0125 means the engine failed to reach the required temperature (typically around 160°F) within a predetermined time window to enter closed-loop fuel management. In open loop, the car runs rich, dropping fuel economy by 10-20%. A thermostat stuck open is the primary cause in over 80% of vehicles with this code.