P0125

COMPONENT DESCRIPTION
The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.





ON BOARD DIAGNOSIS LOGIC

DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

CAUTION:
Be careful not to overheat engine.

NOTE:
- If both DTC P0115 (0103) and P0125 (0908) are displayed, first perform "TROUBLE DIAGNOSIS FOR DTC P0115".
- If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.





With Consult
(1) Turn ignition switch "ON".
(2) Select "DATA MONITOR" mode with CONSULT
(3) Check that "COOLAN TEMP/S" is above 10°C(50°F) If it is above 10°C, the test result will be OK.
If it is below 10°C, go to following step.
(4) Start engine and run it for 65 minutes at idle speed. If "COOLAN TEMP/S" increases to more than 10°C (50°F) within 65 minutes, stop engine because the test result will be OK.

OR

With Generic Tool
(1) Turn ignition switch "ON".
(2) Select "Mode 1" with GST
(3) Check that engine coolant temperature is above 10°C(50°F).
If it is above 10°C (50°F), the test result will be OK.
If it is below 10°C (50°F), go to following step.
(4) Start engine and run it for 65 minutes at idle speed.
If engine coolant temperature increases to more than 10°C (50°F) within 65 minutes, stop engine because the test result will be OK.
(5) Select "MODE 7" with GST

OR








Without Scan Tool
(1) Turn ignition switch "ON".
(2) Check that voltage between ECM terminal (51) and ground is less than 3.8V.
If it is less than 3.8V, the test result will be OK.
If it is over 3.8V, go to following step.
(3) Start engine and run it for 65 minutes at idle speed and measuring voltage between ECM terminal (51) and ground.
If the voltage decreases to less than 3.8V within 65 minutes, stop engine because the test result will be OK.
(4) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(5) Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.





DIAGNOSTIC PROCEDURE





WIRING DIAGRAM











COMPONENT INSPECTION
Engine Coolant Temperature Sensor
Check resistance as shown in the figure.
If NG, replace engine coolant temperature sensor.