P0125Insufficient Coolant Temperature for Closed Loop Fuel Control
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Closed-loop mixture control using the oxygen sensors is only released once the coolant has reached a minimum temperature. CARB requires that this happens within set times – from 2006 two minutes if the engine starts up to 8 °C below the release temperature, five minutes if 8–19 °C below. P0125 means it took too long. Ford checks once per cold start and fails if coolant is still below 10 °C while its model already expects over 27 °C; Mitsubishi expects about 7 °C within 90–300 s and also fails if coolant drops back below 40 °C. Long idling suspends the test. Usual causes are a thermostat stuck open or a sensor reading too cold. GM does not use this code in the tables checked.
- What you may notice
- Check engine light on
- Engine warms up slowly, heater stays cold for a long time
- Higher consumption during warm-up
- Temperature gauge reads low
- Likely causes
- LikelyThermostat stuck open (especially in cold weather)
- LikelyCoolant sensor reading too cold or slow (drift, contact resistance)
- PossibleLow coolant level or air at the sensor
- RareMuch idling or coasting in frost
- RareEngine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.