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Toyota Sienna Service Manual: Insufficient Coolant Temperature for Closed Loop Fuel Control

Toyota Sienna Service Manual / Engine / 2Gr-fe engine control system / Sfi system / Diagnostic trouble code chart / Insufficient Coolant Temperature for Closed Loop Fuel Control

Insufficient Coolant Temperature for Closed Loop Fuel Control

DESCRIPTION

Refer to DTC P0115 (See page ES-133).

Insufficient Coolant Temperature for Closed Loop Fuel Control

MONITOR DESCRIPTION

The resistance of the ECT sensor varies in proportion to the actual ECT. 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 ECT is monitored through this signal. If the ECT 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 ECT is 0°C (32°F) at engine start. After 5 minutes running time, the ECT 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.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

Refer to DTC P0115 (See page ES-134).

INSPECTION PROCEDURE

HINT

1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0125)

(a) Connect the intelligent tester to the DLC3.

(b) Turn the ignition switch to the ON position.

(c) Turn the tester on.

(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(e) Read the DTCs.

Result

HINT:

If any DTCs other than P0125 are output, troubleshoot those DTCs first.

2 INSPECT THERMOSTAT

(a) Remove the thermostat (See page CO-16).

(b) Check the valve opening temperature of the thermostat (See page CO-17).

Standard: 80 to 84°C (176 to 183°F)

HINT:

In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

(c) Reinstall the thermostat (See page CO-17).

3 CHECK COOLING SYSTEM

(a) Check for defects in the cooling system that might cause the system to be too cold, such as abnormal radiator fan operation or any modifications.

REPLACE ENGINE COOLANT TEMPERATURE SENSOR (See page ES-516)

Throttle / Pedal Position Sensor / Switch "A" Circuit Range / Performance Problem
HINT: This DTC relates to the Throttle Position (TP) sensor. DESCRIPTION Refer to DTC P0120 (See page ES-145). MONITOR DESCRIPTION The ECM uses the TP sensor to monitor the throttle valve ...

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
HINT: This DTC relates to the thermostat. DESCRIPTION This DTC is set when the Engine Coolant Temperature (ECT) does not reach 75°C (167°F) despite sufficient engine warm-up time. MON ...

Other materials:

Actuator Supply Voltage Circuit / Open
DESCRIPTION The ECM monitors the output voltage to the throttle actuator. This self-check ensures that the ECM is functioning properly. The output voltage is usually 0 V when the ignition switch is turned off. If the output voltage is higher than 7 volts when the ignition switch is turned ...

Drive shaft system
PRECAUTION 1. NOTICE OF REMOVING AND INSTALLING FRONT DRIVE SHAFT ASSEMBLY RH (a) When removing and installing the front drive shaft assembly RH in a 4WD vehicle, be sure to first drain all the transaxle oil and transfer oil. If removal and installation is carried out without draining these oi ...

Data list / active test
1. READ DATA LIST HINT: Using the intelligent tester to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be disco ...

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