P0125

NOTE: If DTC P0125 (0908) is displayed with P0115 (0103), first perform "DTC P0115 ENGINE COOLANT TEMPERATURE (ECTS) SENSOR".

Reference Data:

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:

DTC Confirmation Procedure

CAUTION: Be careful not to overheat engine.

NOTE: If "DTC 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 (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 "COOLAN TEMP/S" increases to more than 10°C (50°F) within 65 minutes, stop engine because the test result will be OK.
5. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

With GST
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.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.







Without Scan Tool
1. Turn ignition switch "ON".
2. Check that voltage between ECM terminal 59 (Engine coolant temperature sensor signal) 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 measuring voltage between ECM terminal 59 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.
6. If 1st trip DTC is detected, go to "Diagnostic Procedure" below.

EC-ECTS-01:

EC-ECTS-01 Connectors View:

Wiring Diagram

Diagnostic Procedure

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

Step 6:

Component Inspection
Check resistance as shown in the figure.


Temperature °C (°F) Resistance K Ohms
20 (68) 21 - 2.9
50 (122) 0.68 - 1.0
90 (194) 0.236 - 0.260

If NG, replace engine coolant temperature sensor.