P0125

DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL

GENERAL DESCRIPTION
When the engine is first started, the fuel control system operates in an open loop operation ignoring the HO2S(Heated Oxygen Sensor) signal and calculating the air/fuel ratio based on inputs from the engine coolant temperature, the throttle position and the mass air flow sensors. The PCM will begin by using the oxygen sensor signal for controlling the fuel the fuel delivery(closed loop) when the following conditions are met:
- engine has run a minimum amount of time at engine start up.
- The HO2S has a varying voltage output showing that it is hot enough to operate properly.
- The ECT has increased a minimum amount based on the ECT at start up.

The PCM monitors the amount of time for the cooling system to achieve closed loop operating temperature. The engine coolant temperature sufficient to allow closed loop operation is not achieved within a predetermined time frame, PCM sets DTC.

DTC DESCRIPTION
Checking time and coolant temperature under detecting condition, if the engine coolant temperature dose not exceed the coolant temperature threshold before the determinated period elapses, PCM sets P0125. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition:

Specification:

Schematic Diagram:

MONITOR DTC STATUS
1. Check DTC Status
1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.




4. Read "DTC Status" parameter.
5. Is parameter displayed "Present fault"?

YES - Go to "Component inspection" procedure.

NO - Fault is intermittent, go to "Verification of Vehicle Repair" procedure.

COMPONENT INSPECTION
1. IG "OFF" and disconnect ECTS connector.
2. Remove it.

Specification:

3. Measure resistance between signal and ground terminals of ECTS connector as the temperature rises.
4. Are the measured resistance within specification?

YES - Clear DTC and Test-drive under enable conditions above mentioned. After the test, If this DTC is set, recheck it thoroughly. If not, it is intermittent fault, go to "verification of vehicle Repair" procedure.

NO
- Substitute with a known - good ECTS and check for proper operation.
- If the problem is connected, 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 scantool and select "DTC" button.
2. Press "DTC Status button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3. Read "DTC Status" parameter
4. Is parameter displayed 'History(Not Present) fault"?

YES - System performing to specification at this time. Clear the DTC.

NO - Go to the applicable troubleshooting procedure.