G16E-GTS (ENGINE CONTROL): SFI SYSTEM: P012F62; Engine Coolant Temperature/Engine Oil Temperature Signal Compare Failure; 2023 - 2025 MY GR Corolla [09/2022

The engine is equipped with an engine coolant temperature sensor and an engine oil temperature sensor. The engine coolant temperature sensor and engine oil temperature sensor each have a built-in thermistor. As the temperature decreases, the thermistor resistance increases and as the temperature increases, the thermistor resistance decreases. The voltages at the respective terminals of the ECM change in accordance with the changes in the resistance of the thermistors. The ECM performs control based on these voltages.

MONITOR DESCRIPTION

After the engine has stopped for 5 hours or more, the ECM monitors the voltage of the engine coolant temperature sensor and engine oil temperature sensor. If the difference between the readings of the engine coolant temperature and engine oil temperature is higher than 20°C (36°F), the ECM determines that there is a malfunction in the engine coolant temperature sensor circuit or engine oil temperature sensor circuit, and stores a DTC and illuminates the MIL.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

HINT:

After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
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When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.
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Connect the GTS to the DLC3.
Turn the ignition switch to ON [A].
Turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the ignition switch off.
With the engine stopped, leave the vehicle as is for 5.5 hours or more [B].
Turn the ignition switch to ON [C].
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Trouble Codes [D].
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P012F62.

Check the DTC judgment result.

GTS Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

HINT:

If the judgment result is NORMAL, the system is normal.
If the judgment result is ABNORMAL, the system is malfunctioning.
If the judgment result is INCOMPLETE, perform steps [B] through [D] again.
[B] to [D]: Normal judgment procedure.
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
When clearing the permanent DTCs, do not disconnect the cable from the battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

CAUTION / NOTICE / HINT

Read Freeze Frame Data using the GTS. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. When troubleshooting, Freeze Frame Data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

Powertrain > Engine > Trouble Codes

(a) Using the GTS, read the values displayed in the Freeze Frame Data recorded in step 1.

Powertrain > Engine > DTC(P012F62) > Freeze Frame Data

HINT:

When the engine is cold, the value of the engine coolant temperature, engine oil temperature and intake air temperature should be approximately the same.
If the result is not as specified, check that there are no heat sources such as a block heater in the engine compartment.
Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.
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(a) Using the GTS, read the values displayed in the Freeze Frame Data recorded in step 1.

Powertrain > Engine > DTC(P012F62) > Freeze Frame Data

When the engine is cold, the value of the engine coolant temperature, engine oil temperature and intake air temperature should be approximately the same.