Except For California

P0128 THERMOSTAT FUNCTION

DTC Logic


DTC DETECTION LOGIC

NOTE:
If DTC P0128 is displayed with DTC P0300, P0301, P0302, P0303 or P0304, first perform the trouble diagnosis for DTC P0300, P0301, P0302, P0303, P0304. Except For California.
Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long enough.
This is due to a leak in the seal or the thermostat stuck open.






DTC CONFIRMATION PROCEDURE


1. PRECONDITIONING

If DTC CONFIRMATION PROCEDURE has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.
TESTING CONDITION:
-For best results, perform at ambient temperature of -10�C (14�F) or higher.
-For best results, perform at engine coolant temperature of -10�C (14�F) to 52�C (126�F).
-Before performing the following procedure, do not fill with the fuel.
- GO TO 2.

2. PRECONDITIONING-II

With CONSULT
1.Turn ignition switch ON.
2.Check the following conditions:





3.Select "DATA MONITOR" mode of "ENGINE" using CONSULT.
4.Check the following conditions:





Is the condition satisfied?
YES- GO TO 3.
NO- 1.Satisfy the condition.
2.GO TO 3.

3. PERFORM DTC CONFIRMATION PROCEDURE-I

With CONSULT
1.Start engine.
2.Drive the vehicle until the following condition is satisfied.

CAUTION:
Always drive vehicle at safe speed.
-STEP 1
Drive the vehicle under the conditions instructed below until the difference between "COOLANT TEMP/S" and "FUEL T/TMP SE" becomes at least 24�C (43�F).





*: Example





-STEP 2 (MT models)
Drive the vehicle at 60 km/h (37 MPH) or more with the difference between "COOLANT TEMP/S" and "FUEL
T/TMP SE" maintained at 24�C (43�F) or more.
STEP 2 (CVT models)
Drive the vehicle at 50 km/h (32 MPH) or more with the difference between "COOLANT TEMP/S" and "FUEL
T/TMP SE" maintained at 24�C (43�F) or more.
NOTE:
Keep the accelerator pedal as steady as possible during cruising.
-STEP 3 (MT models)
Drive the vehicle at 60 km/h (37 MPH) or more until "COOLANT TEMP/S" increases by 6�C (11�F).
STEP 3 (CVT models)
Drive the vehicle at 50 km/h (32 MPH) or more until "COOLANT TEMP/S" increases by 6�C (11�F).
NOTE:
Keep the accelerator pedal as steady as possible during cruising.
Is the condition satisfied?
YES- GO TO 4.
NO- GO TO 1.

4. PERFORM DTC CONFIRMATION PROCEDURE-II

With CONSULT
1.Drive the vehicle until the following condition is satisfied.






CAUTION:
Always drive vehicle at safe speed.
2.Check 1st trip DTC.
Is 1st trip DTC detected?
YES- Proceed to .
NO- INSPECTION END


Diagnosis Procedure


1. CHECK ENGINE COOLANT TEMPERATURE SENSOR

.
Is the inspection result normal?
YES- GO TO 2.
NO- Replace engine coolant temperature sensor. Exploded View.

2. CHECK THERMOSTAT

Inspection.
Is the inspection result normal?
YES- INSPECTION END
NO- Replace thermostat. Removal And Installation.


Component Inspection


1. CHECK ENGINE COOLANT TEMPERATURE SENSOR

1.Turn ignition switch OFF.
2.Disconnect engine coolant temperature sensor harness connector.
3.Remove engine coolant temperature sensor. Exploded View.
4.Check resistance between engine coolant temperature sensor terminals by heating with hot water as shown in the figure.





Is the inspection result normal?
YES- INSPECTION END
NO- Replace engine coolant temperature sensor. Exploded View.