DTC P0128
DTC P0128 : Cooling System Malfunction
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| P0128 Cooling System Malfunction |
DTC (PGM-FI)
- Radiator fan control command check
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
-3. Turn the blower switch off.
-4. Check the parameter (s) below with the HDS.
Signal Threshold Current conditions Values Unit Values Unit FAN HIGH CTRL OFF FAN LOW CTRL OFF Do the current condition (s) match the threshold?
YES
Go to step 2.
NO
Wait until the FAN HIGH CTRL and the FAN LOW CTRL are OFF, then go to step 2.
- Radiator fan operation check
-1. Check the radiator fan operation.
Does the radiator fan keep running?
YES
Go to step 3.
NO
Go to step 4.
- Radiator fan circuit and radiator fan relay check
-1. Check the radiator fan circuit and the radiator fan relay.
Is it OK?
YES
Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P0128 goes away and the PCM was updated, troubleshooting is complete. If DTC P0128 goes away and the PCM was substituted, replace the original PCM .
NO
Repair the radiator fan circuit, and the radiator fan relay.
- Problem verification
-1. Let the engine cool until the coolant temperature is 104 deg. F (40 deg. C) or less.
-2. Note the value of ECT SENSOR 1 and ECT SENSOR 2 in the DATA LIST with the HDS.
Signal Current conditions Values Unit ECT SENSOR 1 ECT SENSOR 2 -3. Start the engine, and let it idle.
-4. Let the engine idle until ECT SENSOR 1 goes up 40 deg. F (22 deg. C) or more from the recorded start temperature.
Signal Current conditions Values Unit ECT SENSOR 1 -5. Check ECT SENSOR 2 in the DATA LIST with the HDS.
Signal Current conditions Values Unit ECT SENSOR 2 -6. Compare the recorded start value of ECT SENSOR 2 and the present value of ECT SENSOR 2.
Did the temperature rise 13 deg. F (7 deg. C) or more?
YES
Test the thermostat and replace it if needed .
NO
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 PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot .