- Engine Coolant Temperature (ECT) sensor
- Cooling system
- Thermostat
| Last Modified: 4-30-2014 | 6.6 C | Doc ID: RM000000T9P00GX |
| Model Year: 2006 | Model: LX470 | Prod Date Range: [05/2005 - 01/2006] |
| Title: 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0125; Insufficient Coolant Temperature for Closed Loop Fuel Control; 2006 MY LX470 [05/2005 - 01/2006] | ||
|
DTC |
P0125 |
Insufficient Coolant Temperature for Closed Loop Fuel Control |
DESCRIPTION
Refer to DTC P0115
![2006 MY LX470 [05/2005 - ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0115,P0117,P0118; Engine Coolant Temperature Circuit+](../../../../stylegraphics/info.gif "2006 MY LX470 [05/2005 - ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0115,P0117,P0118; Engine Coolant Temperature Circuit+")
.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P0125 |
Engine coolant temperature hardly changes for 2 minutes after engine start (2 trip detection logic) |
|
|
P0125 |
Engine coolant temperature hardly changes for 5 minutes after engine start (2 trip detection logic) |
|
|
P0125 |
Engine coolant temperature hardly changes for 20 minutes 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 5 minutes 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.
This monitor runs when the ECT at engine start was -6.6°C (20°F) and the engine has run 5 minutes.
MONITOR STRATEGY
|
Related DTCs |
P0125: Insufficient engine coolant temperature for closed-loop fuel control |
|
Required Sensors/Components (Main) |
Engine coolant temperature sensor |
|
Required Sensors/Components (Related) |
Cooling system, thermostat |
|
Frequency of Operation |
Once per driving cycle |
|
Duration |
2 minutes: Closed-loop enable temperature -8.34°C (15°F) or more 5 minutes: Closed-loop enable temperature -19.45 to 8.34°C (35 to 15°F) 20 minutes: Less than closed-loop enable temperature -19.45°C (35°F) |
|
MIL Operation |
2 driving cycles |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All
|
Monitor will run whenever these DTCs are 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 |
"Closed-loop enable temperature -8.34°C (15°F)" or more |
|
Engine |
Running |
|
Fuel cut |
OFF |
Case 2
|
Engine coolant or intake air temperature at engine start |
Between "Closed-loop enable temperature -19.45°C (35°F)" and "Closed-loop enable temperature -8.34°C (15°F)" |
|
Engine |
Running |
|
Fuel cut |
OFF |
Case 3
|
Engine coolant or intake air temperature at engine start |
Lower than "Closed-loop enable temperature -19.45°C (35°F)" or more |
|
Engine |
Running |
|
Fuel cut |
OFF |
|
Idle |
OFF |
TYPICAL MALFUNCTION THRESHOLDS
|
Engine coolant temperature |
Less than closed-loop enable temperature |
WIRING DIAGRAM
Refer to DTC P0115
.
INSPECTION PROCEDURE
HINT:
- If DTCs P0115, P0116, P0117, P0118 and P0125 are output simultaneously, an ECT sensor circuit may be open or short. Perform the troubleshooting of DTC P0115, P0117 or P0118 first.
- Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
|
1. |
CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0125) |
(a) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
(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 |
|
|
|
2. |
INSPECT THERMOSTAT |
(a)
Remove the thermostat
.
(b) Check the valve opening temperature of the thermostat.
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.
| NG |
|
|
|
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 a modified cooling system.
| NG |
|
| OK |
|
|
|