P0125

Severity medium

AUTO

Insufficient Coolant Temperature for Closed Loop Fuel Control

Also searched as: P0125 code, insufficient coolant temperature closed loop

OBD-II scanner plugged into a car diagnostic port showing a trouble code
OBD-II codes: read the code, test the component, clear it and re-check.

What it means

P0125 means the engine took too long to warm up enough to enter closed-loop fuel control. A thermostat stuck open is the most common cause. You may notice the temperature gauge staying low and weak cabin heat.

Applies to: OBD-II vehicles 1996+ (US), EOBD vehicles (EU petrol 2001+)

How to fix P0125

  1. Check the coolant level when the engine is cold
  2. Watch the temperature gauge or scan tool data; slow warm-up suggests a thermostat stuck open
  3. Replace the thermostat with the correct temperature rating
  4. Test the engine coolant temperature sensor and its wiring
  5. Clear the code and verify with a full warm-up drive

Why it happens

A thermostat stuck open, low coolant, or a faulty coolant temperature sensor delays warm-up.

FAQ

Can I drive with P0125?

Usually yes, but fuel economy suffers and the engine runs rich for longer. Fix it soon, especially before winter.

Related errors

P0113P0137P0122P0335P0341P0401P0420P0430

Source: open OBD-II DTC database · fixes written and reviewed by the editors (see our editorial policy)

Last updated: