P0128

DTC P0128: Cooling System Malfunction (2006 model)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Turn the blower switch OFF.
4. Turn the A/C switch OFF.
5. Check the FAN CTRL in the DATA LIST with the HDS.

Is it OFF?

YES - Go to step 6.

NO - Wait until the FAN CTRL is off, then go to step 6.

6. Check the radiator fan operation.

Does the radiator fan keep running?

YES - Check the radiator fan circuit. If the circuit is OK, go to step 20.

NO - Go to step 7.

7. Let the engine cool until the coolant temperature is 104 degrees F (40 degrees C) or less.
8. Note the value of ECT SENSOR 1 and ECT SENSOR 2 in the DATA LIST with the HDS.
9. Start the engine, and let it idle.
10. Let the engine idle until ECT SENSOR 1 goes up 49 degrees F (27 degrees C) or more from the recorded temperature.
11. Check ECT SENSOR 2 in the DATA LIST with the HDS.
12. Compare the value of recorded ECT SENSOR 2 and the value of present ECT SENSOR 2.

Did temperature rise 17 degrees F (9.5 degrees C) or more7

YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM.

NO - Test the thermostat, then go to step 13.

13. Turn the ignition switch ON (II).
14. Reset the ECM/PCM with the HDS.
15. Let the engine cool until the coolant temperature is between 21 degrees F (- 6 degree C) and 104 degrees F (40 degrees C).
16. Do the ECM/PCM idle learn procedure.
17. Test-drive at a steady speed between 15-75 mph (24-120 km/h) for 10 minutes.
18. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated7

YES - If DTC P0128 is indicated, check the cooling system, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - Go to step 19.

19. Monitor the OBD STATUS for DTC P0128 in the DTCs MENU with the HDS.

Does the screen indicate PASSED7

YES - Troubleshooting is complete.

NO - If the screen indicates FAILED, check the cooling system, then go to step 1. If the screen indicates NOT COMPLETED, go to step 15 and recheck.

20. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
21. Let the engine cool until the coolant temperature is between 21 degrees F (-6 degree C) and 104 degrees F (40 degrees C).
22. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
23. Test-drive at a steady speed between 15-75 mph (24-120 km/h)for 10 minutes.
24. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P0128 is indicated, check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM.