2Tr-Fe Engine Control. Dtc P2195 Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

The air fuel ratio sensor generates a voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio and regulates the fuel injection time. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The air fuel ratio sensor is of the planar type and is integrated with a heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows through the heater to heat the sensor in order to facilitate accurate air-fuel ratio detection. In addition, the sensor and heater portions are the narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, thereby accelerating the sensor activation.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. For the most efficient use of the Three-Way Catalytic Converter (TWC), the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
*: The value changes inside the ECM. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

Hilux. Tgn26, 36 Kun25, 26, 35, 36 Ggn25.2Tr-Fe Engine Control.Sfi System (W/ Secondary Air Injection System).
Dtc
P2195 Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)

DTC No.	DTC Detection Condition	Trouble Area
P2195	Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): (a) Air fuel ratio sensor voltage is higher than 3.8 V. (b) Heated oxygen sensor voltage is 0.21 V or higher.	Open or short in air fuel ratio sensor (Sensor 1) circuit Air fuel ratio sensor (Sensor 1) Air fuel ratio sensor heater (Sensor 1) Integration relay Air fuel ratio sensor heater and integration relay circuits Air induction system Fuel pressure Fuel injector assembly ECM
P2196	Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic): (a) Air fuel ratio sensor voltage is below 2.8 V. (b) Heated oxygen sensor voltage is below 0.59 V.	Open or short in air fuel ratio sensor (Sensor 1) circuit Air fuel ratio sensor (Sensor 1) Air fuel ratio sensor heater (Sensor 1) Integration relay Air fuel ratio sensor heater and integration relay circuits Air induction system Fuel pressure Fuel injector assembly ECM

HINT:

When either of these DTCs is stored, check the air fuel ratio sensor output voltage by entering the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Voltage B1S1.
Short-term fuel trim values can also be read using the intelligent tester.
The ECM maintains the voltages at the A1A+ and A1A- terminals of the ECM at a constant level. Therefore, the air fuel ratio sensor output voltage cannot be confirmed without using the intelligent tester.
If the air fuel ratio sensor is malfunctioning, the ECM stores DTC P2195 or P2196.

MONITOR DESCRIPTION

Sensor voltage detection monitor
Under air-fuel ratio feedback control, if the air fuel ratio sensor output voltage is below 2.8 V (very rich condition) for 5 seconds despite the rear heated oxygen sensor output voltage being below 0.59 V, the ECM stores DTC P2196. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the rear heated oxygen sensor output voltage being 0.21 V or higher, DTC P2195 is stored.

MONITOR STRATEGY

Required Sensors/Components (Main)	Air fuel ratio sensor
Required Sensors/Components (Related)	Heated oxygen sensor
Frequency of Operation	Continuous: Sensor voltage detection monitor
Duration	20 to 30 seconds: Sensor voltage detection monitor

TYPICAL ENABLING CONDITIONS

Sensor Voltage Detection Monitor
Time after engine start	30 seconds or more
Fuel system status	Closed loop

TYPICAL MALFUNCTION THRESHOLDS

Sensor Voltage Detection Monitor (Lean Side Malfunction P2195)
Rear heated oxygen sensor voltage	0.21 V or higher
Air fuel ratio sensor voltage	Higher than 3.8 V

Sensor Voltage Detection Monitor (Rich Side Malfunction P2196)
Rear heated oxygen sensor voltage	Below 0.59 V
Air fuel ratio sensor voltage	Below 2.8 V

CONFIRMATION DRIVING PATTERN

HINT:

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

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON.
Turn the intelligent tester on.
Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the intelligent tester on.
Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].
Drive the vehicle at approximately 60 km/h (38 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 and ECT / DTC [C].
Read the pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Intelligent tester 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
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

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 or N/A, perform the following procedure.

Drive the vehicle at a speed between 75 and 100 km/h (47 and 63 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 and ECT / DTC [E].
Read the pending DTCs.
HINT:
1. If a pending DTC is output, the system is malfunctioning.
2. If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Intelligent tester 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
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.

WIRING DIAGRAM

Refer to DTC P2237 (HILUX_TGN26 RM000000XOK0DEX_06.html).

INSPECTION PROCEDURE

HINT:

Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
Sensor 1 refers to the sensor mounted in front of the Three-way Catalytic Converter (TWC) and located near the engine assembly.
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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.
A low air fuel ratio sensor 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 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.

1.CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the intelligent tester on.

Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Result
Result
Proceed to
P2195 or P2196 is output
A
P2195 or P2196 and P0136, P0137 or P0138 are output
A
P2195 or P2196 and other DTCs are output
B
HINT:
If any DTCs relating to the air fuel ratio sensor (DTCs for the air fuel ratio sensor heater or air fuel ratio sensor admittance) are output, troubleshoot those DTCs first.

Result
Result	Proceed to
P2195 or P2196 is output	A
P2195 or P2196 and P0136, P0137 or P0138 are output	A
P2195 or P2196 and other DTCs are output	B

GO TO DTC CHART (HILUX_TGN26 RM0000032SF041X.html)

A

2.CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST

Has the vehicle run out of fuel in the past?

Go to step 4

YES

3.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the intelligent tester on.

Clear the DTCs (HILUX_TGN26 RM000000PDK130X.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON and turn the intelligent tester on.

Start the engine and warm it up.

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

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Result
Result
Proceed to
NORMAL (DTC is not output)
A
ABNORMAL (DTC P2195 or P2196 is output)
B

Result
Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P2195 or P2196 is output)	B

Go to step 4

DTC CAUSED BY RUNNING OUT OF FUEL

4.READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF AIR FUEL RATIO SENSOR)

Connect the intelligent tester to the DLC3.

Start the engine.

Turn the intelligent tester on.

Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for 90 seconds.

Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

Perform the Control the Injection Volume for A/F Sensor operation with the engine idling.

Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the intelligent tester.

HINT:

Change the fuel injection volume within the range of -12.5% to +12.5%. The injection volume can be changed in fine gradations.
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

Intelligent tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 (Air fuel ratio)	+12.5%	Rich	Below 3.1 V
AFS Voltage B1S1 (Air fuel ratio)	-12.5%	Lean	Higher than 3.4 V
O2S B1S2 (Heated oxygen)	+12.5%	Rich	Higher than 0.55 V
O2S B1S2 (Heated oxygen)	-12.5%	Lean	Below 0.4 V

Result
Status of AFS Voltage B1S1	Status of O2S B1S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Proceed to
Lean	Lean	Actual air fuel ratio lean	A
Rich	Rich	Actual air fuel ratio rich	A
Lean	Lean/Rich	Air fuel ratio sensor malfunction	B
Rich	Lean/Rich	Air fuel ratio sensor malfunction	B
Lean/Rich	Lean/Rich	Normal	B

Lean: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently below 0.4 V.
Rich: During the Control the Injection Volume for A/F Sensor Active Test, the AFS Voltage is consistently below 3.1 V, and the O2S is consistently higher than 0.55 V.
Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output voltage of the heated oxygen sensor alternates correctly.

HINT:

Refer to "Data List / Active Test" [AFS Voltage B1S1 and O2S B1S2] (HILUX_TGN26 RM000000SXS08OX.html).

Go to step 13

A

5.CHECK FOR INTAKE SYSTEM

Check the intake system for vacuum leaks.
OK:
No leaks in intake system.

REPAIR OR REPLACE INTAKE SYSTEM

OK

6.CHECK FOR EXHAUST GAS LEAK

Check for exhaust gas leaks.
OK:
No gas leaks.

REPAIR OR REPLACE EXHAUST SYSTEM

OK

7.CHECK FUEL PRESSURE

Check the fuel pressure (HILUX_TGN26 RM000000YL704TX_01_0002.html).

Go to step 15

OK

8.INSPECT FUEL INJECTOR ASSEMBLY

Check the fuel injector assembly (whether fuel volume is high or low, and whether injector pattern is poor) (HILUX_TGN26 RM000000WQQ076X.html).

REPLACE FUEL INJECTOR ASSEMBLY (HILUX_TGN26 RM000000YLB01MX.html)

OK

9.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor (HILUX_TGN26 RM00000142300YX.html).

NEXT

10.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the intelligent tester on.

Clear the DTCs (HILUX_TGN26 RM000000PDK130X.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON and turn the intelligent tester on.

Start the engine and warm it up.

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

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Result
Result
Proceed to
ABNORMAL (DTC P2195 or P2196 is output)
A
NORMAL (DTC is not output)
B

END

A

11.REPLACE ECM

Replace the ECM (HILUX_TGN26 RM000000VW202TX.html).

NEXT

12.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the intelligent tester on.

Clear the DTC (HILUX_TGN26 RM000000PDK130X.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON and turn the intelligent tester on.

Start the engine and warm it up.

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

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Result
Intelligent tester 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
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

END

13.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor (HILUX_TGN26 RM00000142300YX.html).

NEXT

14.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)

Connect the intelligent tester to the DLC3.

Turn the ignition switch to ON.

Turn the intelligent tester on.

Clear the DTCs (HILUX_TGN26 RM000000PDK130X.html).

Turn the ignition switch off and wait for at least 30 seconds.

Turn the ignition switch to ON and turn the intelligent tester on.

Start the engine and warm it up.

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

Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

Input the DTC: P2195 or P2196.

Check the DTC judgment result.

Result
Result
Proceed to
NORMAL (DTC is not output)
A
ABNORMAL (DTC P2195 or P2196 is output)
B

REPLACE ECM (HILUX_TGN26 RM000000VW202TX.html)

END

15.CHECK FUEL LINE

Check the fuel lines for leaks or blockage.

REPAIR OR REPLACE FUEL LINE

REPLACE FUEL PUMP (HILUX_TGN26 RM000004PZ300BX.html)