H4SO (2.5L SOHC)

DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL

1. OUTLINE OF DIAGNOSIS
Detect the malfunction of engine coolant temperature output property.

Judge as NG when the engine coolant temperature does not rise in driving conditions where it should.

2. COMPONENT DESCRIPTION






3. ENABLE CONDITION

Enable Conditions:

4. GENERAL DRIVING CYCLE
Perform the diagnosis only once after engine starting.

5. DIAGNOSTIC METHOD

Abnormality Judgment
Judge as NG when the malfunction criteria below are met.






Timer for diagnosis after engine starting
a. Timer stop at fuel cut mode.
b. During the driving conditions except a) above, timer counts up.

64 milliseconds + TWCNT milliseconds (at the time of 64 milliseconds)

TWCNT is defined as follows.

TWCNT = 0 (at idle switch ON)

TWCNT at idle switch OFF is shown in the given table.






Judgment value of timer after engine starting
t = 574 - 33 � Ti (seconds)

Ti : The lowest engine coolant temperature after starting the engine

Time Needed for Diagnosis: Undetermined. (It is varied by the lowest engine coolant temperature and engine conditions such as vehicle speed and engine coolant temperature.)

Malfunction Indicator Light Illumination: Illuminates when malfunction occurs in 2 continuous driving cycles.

Normality Judgment
Judge as OK and clear the NG when the malfunction criteria below are met.






6. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

7. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed

8. FAIL SAFE
- Engine coolant temperature sensor process: Engine coolant temperature is fixed at 70 °C (158 °F)
- ISC Feedback: Calculate target engine speed as engine coolant temperature 70 °C (158 °F).
- ISC learning: Not allowed to learn.
- Air conditioner control: Not allowed to turn the air conditioner to ON.
- Radiator fan control: Both main and sub fan turn to ON.
- Tumble generator valve control: Open the tumble generator valve.

9. ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)