P0128

DTC P0116 / P0125 / P0128

DTC Detecting Condition and Trouble Area






Wiring Diagram










DTC Confirmation Procedure

NOTE:

If DTCs other than aimed DTC are previously detected in DTC confirmation procedure, be sure to troubleshoot DTC previously detected.

DTC P0116:

NOTE:

Check to make sure that the following condition is satisfied when using this procedure.

- ECT < 71 °C (159.8 °F)


1) Start engine and warm up to normal operating temperature.
2) Run engine at idle speed for 15 min.

DTC P0125:

NOTE:

Check to make sure that the following condition is satisfied when using this procedure.

- ECT at engine started < -5 °C (23 °F)


3) Start engine and warm up to normal operating temperature.
4) Run engine at idle speed for 5 min.

DTC P0128:

NOTE:

Check to make sure that the following conditions are satisfied when using this procedure.


- IAT at engine started > -10 °C (14 ° F)

- IAT < -10 °C (14 °F)

- -10 °C (14 °F) < ECT at engine started < 56 °C (132.8 °F)


5) Start engine and warm up to normal operating temperature.

DTC Troubleshooting

1.
Was "Engine and Emission Control System Check" performed?
YES -
Go to Step 2.
NO -
Go to Engine and Emission Control System Check Engine and Emission Control System Check.

2. DTC check

Check DTC.

Is there DTC(s) other than P0116, P0125 and P0128?
YES -
Go to applicable DTC(s).
NO -
Go to Step 3.

3. ECT sensor signal circuit and ground circuit check

Turn OFF ignition switch and disconnect connectors from ECT sensor and ECM.
Check for proper terminal connection to ECT sensor and ECM connectors.
If connections are OK, check that ECT sensor signal circuit (A1) and ground circuit (A2) are as follows.
- Wiring harness resistance of each ECT sensor signal circuit and ground circuit is less than 3 ohms.
- Insulation resistance of ECT sensor signal circuit is infinity between ECT sensor connector and vehicle body ground.
- Insulation resistance of wire harness is infinity between ECT sensor signal circuit terminal and each terminal at ECT sensor connector.
- Circuit voltage of each ECT sensor signal circuit and ground circuit is 0 - 1 V with ignition switch in ON position.

Are they in good condition?
YES -
Go to Step 4.
NO -
Repair or replace defective wire harness.

4. ECT sensor check

Check ECT sensor. ECT (Engine Coolant Temperature) Sensor Inspection

Is it in good condition?
YES -
Go to Step 5.
NO -
Replace ECT sensor.

5. Thermostat check

Check thermostat. Thermostat Inspection

Is it in good condition?
YES -
Substitute a know-good ECM and recheck.
NO -
Replace thermostat.