P0125 Engine Coolant Temp-Fuel Control

A lot of common fixes showing this obd2 P0125 code seem to point to replacing the thermostat of the engine cooling system. However, most of the actual fix requires the replacement of the A/F ratio sensor or oxygen sensor (name commonly called for Toyota engines). Always reset the code first to verify this code before making repairs. For maintenance purposes, replace the oxygen sensor if the engine has too many miles. For other types of engines, please contact ATS.

Coolant system facts:

As your engine run, heat energy is always produce and to maintain an ideal condition of working temperature, the system has a radiator to facilitate the heat transfer process. The cooling system has the most important part against wear by way of the thermostat. The thermostats maintain to control the engine temperature inside your engine by varying coolant flow. Example, the thermostat restricts coolant flow when the engine is cold, making the engine reach operating temperature quicker. And when the temperature of the engine increases, the coolant flow is increased also making heat dissapation quicker.

The engine exhaust system removes much of the heat from the engine, but parts like cylinder walls, pistons, and heads can tolerate big amounts of heat. If these parts gets too hot, the oil film will deteriorate and will fail to protect the engine. And this is when your cooling system comes into the picture by taking away the heat generated by the engine.

CODE     Meaning or Description

P010E     Engine Mass Air Flow ckt
P010F     Engine Mass Air Flow variation
P0110     Engine Air Temp Sensor ckt
P0111     Engine Air Temp Sensor ckt
P0112     Engine Air Temp Sensor ckt
P0113     Engine Air Temp Sensor ckt
P0114     Engine Air Temp Sensor ckt
P0115     Coolant Temp Sensor ckt
P0116     Coolant Temp Sensor ckt
P0117     Coolant Temp Sensor ckt
P0118     Coolant Temp Sensor ckt
P0119     Coolant Temp Sensor ckt
P011A     Coolant Temp Sensor ckt
P011B     Coolant Temp-Air Temp variation
P011C     Engine Air Temperature-Air Temperature varition
P011D     Engine Air Temperature-Air Temperature Correlation
P0120     TP Position Sensor ckt
P0121     TP Position Sensor ckt
P0122     TP Position Sensor ckt
P0123     TP Position Sensor ckt
P0124     TP Position Sensor
P0125     Engine Coolant Temp-Fuel Control
P0126     Engine Coolant Temp Operation
P0127     Engine Air Temperature High
P0128     Engine Coolant Thermostat
P0129     Engine Barometric Press
P012A     Engine Turbo-Supercharger Pressure Sensor ckt
P012B     Engine Turbo-Supercharger Pressure Sensor ckt
P012C     Engine Turbo-Supercharger Pressure Sensor ckt
P012D     Engine Turbo-Supercharger Pressure Sensor ckt
P012E     Engine Turbo-Supercharger Pressure Sensor ckt
P0130     Oxygen sensor ckt
P0131     Oxygen sensor ckt
P0132     Oxygen sensor ckt
P0133     Oxygen sensor ckt
P0134     Oxygen sensor ckt
P0135     Oxygen sensor ckt
P0136     Oxygen sensor ckt
P0137     Oxygen sensor ckt

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