P0125

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 ECM will begin by using the oxygen sensor signal for controlling the fuel delivery(closed loop) when the following conditions are met:
- The 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 ECM 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, ECM 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 cosecutive 2 driving cycle.

DTC DETECTING CONDITION





MONITOR DTC STATUS

1. Connect scantool to Data Link Connector(DLC).
2. IG "ON".
3. Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) 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.
3. Measure resistance between terminals 1 and 3 of ECTS connector as the temperature rises.
Specification :





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 corrected, 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. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all rediness test have been verified as " Complete "
5. Are any DTCs present ?
YES
> Go to the applicable troubleshoooting procedure.
NO
> System is performing to specification at this time.