P0128

DTC P0128






GENERAL DESCRIPTION
The Thermostat is a mechanical (thermal) device located in an engine coolant passage that allows passage of coolant into the radiator once the coolant has reached a manufacturer specified temperature called the Regulating Temperature. It has a metallic frame with a spring-loaded,centrally mounted, wax filled cylinder/piston assembly that expands and contracts with changes in temperature, thereby controlling the passage of coolant into the radiator.

DTC DESCRIPTION
If the engine coolant temperature does not reach the specified value within the allocated period, the ECM/PCM sets DTC P0128.

DTC Detecting Condition:

Schematic Diagram - A/T:

Schematic Diagram - M/T:

MONITOR SCANTOOL DATA
1. Connect scantool to DLC(Data Link Cable).
2. Warm up the engine to normal operating temperature.




3. Monitor "ECTS" parameter on scantool.
4. Is the "ECTS" parameter displayed correctly?

YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM/PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure

NO - Go to "Component Inspection" procedure.

COMPONENT INSPECTION
1. Check Thermostat.
a. Check cooling system coolant level and fill if low.
b. Check for a proper cooling system operation. Especially check that cooling and condenser fan working normally.
c. Remove the thermostat and check the following items:
1. Stuck or damaged
2. Verify the temperature at which the valve is open: 80 - 84 °C(176-183.2 °F)

d. Has a problem been found?

YES - Substitute with a known - good Thermostat and check for proper operation. If the problem is corrected, replace Thermostat and go to "Verification of Vehicle Repair" proprocedure.

NO - Go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present ?

YES - Go to the applicable troubleshooting procedure.

NO - System is performing to specification at this time.