DTC Troubleshooting: P0126 (86-3)

DTC P0126:  Insufficient Engine Coolant Temperature

1.Check the ECT SENSOR in the DATA LIST with the HDS.

Is about 20 °C (68 °F) or less indicated?


YES - Go to 2.


NO - Intermittent failure, system is OK at this time. Check the thermostat and the cooling system.n


2.Start the engine, and let it idle 20 minutes.

3.Check the ECT SENSOR in the DATA LIST with the HDS.

Is about 20 °C (68 °F) or less indicated?


YES - Go to 4.


NO - Intermittent failure, system is OK at this time. Check the thermostat and the cooling system.n


4.Turn the ignition switch OFF.

5.Replace the ECT sensor.

6.Turn the ignition switch ON (II).

7.Reset the ECM with the HDS.

8.Allow the engine to cool below 20 °C (68 °F).

9.Start the engine, and let it idle 20 minutes.

10.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0126 is indicated, check for poor connections or loose terminals at the ECT sensor and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Go to 11.

11.Monitor the OBD STATUS for DTC P0126 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?


YES - Troubleshooting is complete.n


NO - If the screen indicates FAILED, check for poor connections or loose terminals at the ECT sensor and the ECM, then go to 1. If the screen indicates NOT COMPLETED, go to 8 and recheck.