DTC P0128

DTC P0128  : Cooling System Malfunction

NOTE:  Before you troubleshoot, review the general troubleshooting information .

DTC (PGM-FI)

1. Cooling 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
   Radiator Fan Control	About 0	%

   Do the current condition (s) match the threshold?

   YES 

   Go to step 2.

   NO 

   Wait until the Radiator Fan Control is about 0 %, then go to step 2.

2. Cooling fan operation check

   -1. Check the cooling fan operation.

   Does the cooling fan keep running?

   YES 

   Go to step 3.

   NO 

   Go to step 4.

3. Cooling fan circuit and RFC relay check

   -1. Turn the vehicle to the ON mode.

   -2. Check the cooling fan circuit and the RFC relay.

   Is it OK?

   YES 

   Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good PCM .

   NO 

   Check the cooling fan circuit and the RFC relay, if they are OK, replace the cooling fan motor .

4. Problem verification

   -1. Turn the vehicle to the ON mode.

   -2. Let the engine cool until the coolant temperature is 104 deg.F (40 deg.C) or less.

   -3. 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

   -4. Enter the maintenance mode, then start the engine .

   -5. 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

   -6. Check ECT Sensor 2 in the DATA LIST with the HDS.

   Signal	Current conditions
   	Values	Unit
   ECT Sensor 2

   -7. Compare the recorded start value of ECT Sensor 2 and the present value of ECT Sensor 2.

   Did the temperature rise 14.4 deg.F (8.0 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 on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the on-board snapshot .