2GR-FE ENGINE CONTROL: SFI SYSTEM: P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control
P0125 - Insufficient Coolant Temperature for Closed Loop Fuel Control
DESCRIPTION
A thermistor, whose resistance value varies according to the engine coolant temperature, is built into the engine coolant temperature sensor.
The structure of the sensor and its connection to the ECM are similar to those of the intake air temperature sensor.
HINT
When any of DTCs P0115, P0117 or P0118 are set, the ECM enters fail-safe mode. During fail-safe mode, the engine coolant
temperature is estimated to be 80锟斤拷C (176锟斤拷F) by the ECM. Fail-safe mode continues until a pass condition is detected.
HINT
When any of these DTCs are set, check the engine coolant temperature by entering the following menus on the Techstream:
Powertrain / Engine / Data List / Coolant Temp.
MONITOR DESCRIPTION
The resistance of the engine coolant temperature sensor varies in proportion to the actual engine coolant temperature. The ECM supplies a constant
voltage to the sensor and monitors the signal output voltage of the sensor. The signal voltage output varies according to the changing resistance of
the sensor. After the engine is started, the engine coolant temperature is monitored through this signal. If the engine coolant temperature sensor
indicates that the engine is not yet warm enough for closed loop fuel control, despite a specified period of time having elapsed since the engine was
started, the ECM interprets this as a malfunction in the sensor or cooling system and sets the DTC.
Example:
The engine coolant temperature is 0锟斤拷C (32锟斤拷F) at engine start. After about 1 minute running time, the engine coolant temperature sensor still indicates
that the engine is not warm enough to begin closed loop fuel (air fuel ratio feedback) control. The ECM interprets this as a malfunction in the sensor
or cooling system and sets the DTC.
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