2ZR-FXE (ENGINE CONTROL): SFI SYSTEM: P2A0026; O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Signal Rate of Change Below Threshold; 2023 - 2025 MY Corolla Corolla HV [09/2022

Although the DTC titles say oxygen sensor, this DTC relate to the air fuel ratio sensor (sensor 1).

MONITOR DESCRIPTION

After the engine is warmed up, the ECM performs air fuel ratio feedback control to maintain the air fuel ratio at the stoichiometric level. In addition, active air fuel ratio control is performed for approximately 30 seconds after preconditions are met in order to measure the air fuel ratio sensor (sensor 1) response rate. During active air fuel ratio control, the ECM forcibly increases and decreases the injection volume by a certain amount, based on the stoichiometric air fuel ratio learned during normal air fuel ratio control, and measures the air fuel ratio sensor (sensor 1) response rate. The ECM receives a signal from the air fuel ratio sensor (sensor 1) while performing active air fuel ratio control and uses it to calculate the air fuel ratio sensor (sensor 1) response rate deterioration level.

If the value for the air fuel ratio sensor (sensor 1) response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and stores the DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

CONFIRMATION DRIVING PATTERN

Performing this confirmation driving pattern will activate the air fuel ratio sensor response monitor.

Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG).
Turn the GTS on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
With the engine running, drive the vehicle at approximately 60 to 100 km/h (37 to 62 mph) for 10 minutes or more in a city area [B].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine / Trouble Codes [C].
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: P2A0026.

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 shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE and no pending DTC is output, perform the following procedure.

With the engine running, drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for 10 minutes [D].
CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine / Trouble Codes [E].
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: P2A0026.

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 shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE, drive the vehicle again under an increased load and then recheck the judgment result.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
Vehicle Control History may be stored in the hybrid vehicle control ECU if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the freeze frame data and Vehicle Control History can be useful for troubleshooting.
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(Select Powertrain in Health Check and then check the time stamp data.)

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If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
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HINT:

DTC P2A0026 may be also stored when the air fuel ratio is stuck at rich or lean.
A low air fuel ratio sensor (sensor 1) voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high air fuel ratio sensor (sensor 1) voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.
Sensor 1 refers to the sensor closest to the engine assembly.
Sensor 2 refers to the sensor farthest away from the engine assembly.
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

Powertrain > Hybrid Control > Utility

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

(g) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / Data List / A/F (O2) Sensor Current B1S1 and O2 Sensor Voltage B1S2.

Powertrain > Engine > Active Test

(h) Change the fuel injection volume using the GTS, and monitor the output voltage of the air fuel ratio sensor (A/F (O2) Sensor Current B1S1) and heated oxygen sensor (O2 Sensor Voltage B1S2) displayed on the GTS.

Lean: While performing the Active Test "Control the Injection Volume for A/F Sensor", the air fuel ratio sensor output voltage (A/F (O2) Sensor Current B1S1) is consistently higher than 0.037 mA, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently below 0.4 V.
Rich: While performing the Active Test "Control the Injection Volume for A/F Sensor", the air fuel ratio sensor output voltage (A/F (O2) Sensor Current B1S1) is consistently below -0.075 mA, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently higher than 0.55 V.
Lean/Rich: While performing the Active Test "Control the Injection Volume for A/F Sensor", the output voltage of the fuel ratio sensor (A/F (O2) Sensor Current B1S1) or heated oxygen sensor (O2 Sensor Voltage B1S2) alternates correctly.
HINT:

Refer to "Data List / Active Test" [A/F (O2) Sensor Current B1S1 and O2 Sensor Voltage B1S2].

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Powertrain > Engine > Clear DTCs

(a) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Powertrain > Engine > Utility

Powertrain > Hybrid Control > Utility

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

(f) Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure and Engine Independent.

Powertrain > Engine > Active Test

(g) Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

HINT:

If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 1).

Perform "Inspection After Repair" after repairing or replacing the intake system.

Perform "Inspection After Repair" after repairing or replacing the exhaust system.

Powertrain > Hybrid Control > Utility

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

(f) Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure and Engine Independent.

Powertrain > Engine > Active Test

(g) Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

HINT:

If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

Powertrain > Engine > Clear DTCs

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.