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Powertrain fault code

P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control

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Not urgent, but fuel use goes up and the heater may blow cooler. Fix it at your next service.

What P0125 means

The engine is taking too long to reach normal operating temperature.

Common causes

  • Thermostat stuck open (most common)
  • Faulty coolant temperature sensor
  • Low coolant level

What to check first

  1. Check the coolant level when the engine is cold.
  2. Watch the live coolant temperature on a scan during a drive.
  3. Ask a workshop to test the thermostat.

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Read your car's codes yourself, free

Plug a cheap ELM327 OBD-II adapter into the port under the dashboard and open the scan tool: Chrome or Edge on a computer with a USB adapter, or Chrome on Android with a Bluetooth LE adapter. It reads and clears codes and shows emissions readiness. It does not work on iPhone.

Open the free scan tool

Need help with P0125?

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Related codes

P0128

General guidance only, not a diagnosis. A qualified mechanic should confirm the cause before you replace parts.