Insufficient Coolant Temperature for Closed Loop Fuel Control
Table of contents
- Possible Causes
- How To Fix
- Tech Notes
- Cost To Diagnose
- When is the code detected
- Possible Symptoms
- Description
P0125 TOYOTA Possible Causes
- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty Engine Coolant Temperature (ECT) sensor
- Engine Coolant Temperature (ECT) sensor harness is open or shorted
- Engine Coolant Temperature (ECT) sensor electrical circuit poor connection
How do I fix code P0125 TOYOTA?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- SPECIAL NOTE: For some Toyota models, the P0125 code is set by the front O2 sensor.
- There are factory service bulletins for the following Toyota models:
- 2003 Toyota Corolla
- 2003 Toyota Matrix
- The service bulletin recommends replacing the O2 sensors to fix the problem.
- 2004-2007 Toyota Prius
- 2004-2007 Toyota Prius Factory Service Bulletin OBDII Code P0125
Cost of diagnosing the P0125 TOYOTA code
The cost of diagnosing the P0125 TOYOTA code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
When is the code detected
The Engine Control Module (ECM) monitors the ECT signal voltage after engine start-up. If, after sufficient time has passed, the sensor still reports that the engine is not warm enough for closed-loop fuel control, the ECM interprets this as a fault in the sensor or cooling system and sets a Detected Trouble Code (DTC).
Example:
The ECT is 0C (32F) at engine start. After 5 minutes running time, the ECT sensor still indicates that the engine is not warm enough to begin active feedback control of the air-fuel ratio. The ECM interprets this as a fault in the sensor or cooling system and sets a DTC.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0125 TOYOTA Description
The Engine Coolant Temperature (ECT) sensor is used to monitor the temperature of the engine coolant. The resistance of the sensor varies with the actual coolant temperature. The Engine Control Module (ECM) applies a voltage to the sensor and the varying resistance of the sensor causes the signal voltage to vary.