Download R.M. 2007::2UZ-FE Engine Control System: SFI System

ES–133
2UZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
DTC
Insufficient Coolant Temperature for Closed
Loop Fuel Control
P0125
DESCRIPTION
Refer to DTC P0115 (See page ES-110).
DTC No.
DTC Detection Condition
Trouble Area
Engine coolant temperature hardly changes for 77
seconds after engine start
(2 trip detection logic)
P0125
Engine coolant temperature hardly changes for 129
seconds after engine start
(2 trip detection logic)
•
•
•
Cooling system
Engine coolant temperature sensor
Thermostat
Engine coolant temperature hardly changes for 1200
seconds after engine start
(2 trip detection logic)
MONITOR 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 ECM applies a voltage to the
sensor and the varying resistance of the sensor causes the signal voltage to vary. The ECM monitors the
ECT signal voltage after engine start-up. If the sensor still reports that the engine is not warmed up
enough for closed-loop fuel control after sufficient time has passed, the ECM interprets this as a fault in
the sensor or cooling system and sets a DTC.
Example:
The ECT is 0°C (32°F) at engine start. After 77 seconds running time, the ECT sensor still indicates that
the engine is not warm enough to begin air-fuel ratio feedback control of the air-fuel ratio. The ECM
interprets this as a fault in the sensor or cooling system and will set a DTC.
MONITOR STRATEGY
Related DTCs
P0125: Insufficient engine coolant temperature for closed-loop fuel control
Required Sensors/Components (Main)
Thermostat, Cooling system
Required Sensors/Components (Related)
Engine coolant temperature sensor, Mass air flow meter
Frequency of Operation
Continuous
Duration
77 seconds: -8.34°C (16.98°F) or more
129 seconds: -19.45 to -8.34°C (-3.01 to 16.98°F)
1200 seconds: Less than -19.45°C (-3.01°F)
MIL Operation
2 driving cycles
Sequence of Operation
None
TYPICAL ENABLING CONDITIONS
The monitor will run whenever this DTC is not present
P0100 - P0103 (MAF sensor)
P0110 - P0113 (IAT sensor)
P0115 - P0118 (ECT sensor)
Case 1
Engine coolant or intake air temperature at engine start
-8.34°C (16.98°F) or higher
Case 2
Engine coolant or intake air temperature at engine start
Between -19.45°C (-3.01°F) and -8.34°C (16.98°F)
Case 3
Engine coolant or intake air temperature at engine start
Lower than -19.45°C (-3.01°F)
ES
ES–134
2UZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
TYPICAL MALFUNCTION THRESHOLDS
Engine coolant temperature sensor output
Less than 0°C (32°F)
WIRING DIAGRAM
Refer to DTC P0115 (See page ES-111).
INSPECTION PROCEDURE
ES
HINT:
• If DTCs P0115, P0116, P0117, P0118 and P0125 are output simultaneously, an ECT sensor circuit
may be open or shorted. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
• Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition
information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame
data can be helpful in determining whether the vehicle was running or stopped, whether the engine
was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the
time of a malfunction.
1
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0125)
(a) Connect the intelligent tester to the DLC3 with CAN VIM.
(b) Turn the ignition switch ON and turn the intelligent tester
ON.
(c) Enter the following menus: DIAGNOSIS / ENHANCED
OBD II / DTC INFO / CURRENT CODES.
(d) Read the DTCs.
Result
Display (DTC Output)
Proceed to
P0125
A
P0125 and other DTCs
B
HINT:
If any other codes besides P0125 is output, perform the
troubleshooting for those codes first.
B
GO TO RELEVANT DTC CHART
A
2
INSPECT THERMOSTAT
(a) Remove the thermostat (See page CO-9).
(b) Check the valve opening temperature of the thermostat
(See page CO-9).
OK:
Valve opening temperature is 80 to 84°C (176 to
183°F)
HINT:
Also check that the valve is completely closed below the
opening temperature shown above.
(c) Reinstall the thermostat (See page CO-10).
NG
REPLACE THERMOSTAT
2UZ-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
ES–135
OK
3
CHECK COOLING SYSTEM
(a) Check that there is a defect in the cooling system which
causes overcool, such as abnormal radiator fan
operation, modified cooling system and so on.
NG
REPAIR OR REPLACE COOLING SYSTEM
OK
REPLACE ENGINE COOLANT TEMPERATURE SENSOR
ES