Although the DTC titles say oxygen sensor, these DTCs relate to the Air Fuel Ratio (A/F) sensor.
Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

The A/F 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 A/F sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The A/F sensor is 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 into the heater to heat the sensor in order to facilitate accurate oxygen concentration 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, therefore the sensor activation is accelerated.

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 TWC is used. For the most efficient use of the 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 A/F sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.

Description DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

DTC Code	DTC Detection Condition	Trouble Area
P2195 P2197	Conditions (a) and (b) continue for 2 seconds or more (2 trip detection logic): (a) The Air Fuel Ratio (A/F) sensor voltage is more than 3.8 V. (b) The Heated Oxygen (HO2) sensor voltage is 0.15 V or more.	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor (bank 1, 2 sensor 1) heater A/F sensor heater circuits Integration relay Air induction system circuits Fuel pressure Fuel injector ECM
P2195 P2197	While fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio (A/F) sensor current is 3.6 mA or more for 3 seconds (2 trip detection logic).	A/F sensor ECM
P2196 P2198	Conditions (a) and (b) continue for 2 seconds or more (2 trip detection logic): (a) The A/F sensor voltage is less than 2.8 V. (b) The HO2 sensor voltage is less than 0.6 V.	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor (bank 1, 2 sensor 1) heater A/F sensor heater circuits Air induction system Integration relay Fuel pressure Fuel injector ECM
P2196 P2198	While fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio (A/F) sensor current is less than 1.4 mA for 3 seconds (2 trip detection logic).	A/F sensor ECM

HINT:

DTCs P2195 and P2196 indicate malfunctions related to the bank 1 A/F sensor circuit.
DTCs P2197 and P2198 indicate malfunctions related to the bank 2 A/F sensor circuit.
Bank 1 refers to the bank that includes cylinder No. 1.
Bank 2 refers to the bank that includes cylinder No. 2.
When any of these DTCs are stored, check the A/F sensor voltage output by entering the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / AFS Voltage B1S1 or AFS Voltage B2S1.
The short-term fuel trim values can also be read using the intelligent tester.
The ECM regulates the voltages at the A1A+, A2A+, A1A- and A2A- terminals of the ECM to a constant level. Therefore, the A/F sensor voltage output cannot be confirmed without using the intelligent tester.
If a A/F sensor malfunction is detected, the ECM stores a DTC.

Wiring diagram

Confirmation driving pattern

CAUTION:

Strictly observe posted speed limits, traffic laws, and road conditions when performing these drive patterns.

HINT:

This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.

Confirmation driving pattern DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the intelligent tester on.
(d) Clear DTCs .
(e) Start the engine, and warm it up until the ECT reaches 75°C (167°F) or higher.
(f) Enter the following menus to check the fuel-cut status: Powertrain / Engine and ECT / Data List / All Data / Idle Fuel Cut.
(g) Drive the vehicle at between 60 km/h (38 mph) and 120 km/h (75 mph) for at least 10 minutes.
(h) Shift the transmission to 2nd gear.
(i) Drive the vehicle at the proper vehicle speed to perform fuel-cut operation (refer to the following HINT).
HINT:

Fuel-cut is performed when the following conditions are met:
1. The accelerator pedal is fully released.
2. The engine speed is 2500 rpm or more (fuel injection returns at 1000 rpm).
(j) Accelerate the vehicle to 64 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds.
(k) Soon after performing step (j) above, release the accelerator pedal for at least 4 seconds without depressing the brake pedal in order to execute fuel-cut control.
(l) Allow the vehicle to decelerate until the vehicle speed decreases to less than 10 km/h (6 mph).
(m) Repeat steps (h) through (k) above at least 3 times in one driving cycle.
HINT:

Completion of all O2S (A/F) Monitor is required to change the value in Data List.

Inspection procedure

HINT:

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the air fuel ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the intelligent tester.

Connect the intelligent tester to the DLC3.
Start the engine and turn the intelligent tester on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
On the intelligent tester, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume.)
Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2, or AFS Voltage B2S1 and O2S B2S2) displayed on the intelligent tester.

HINT:

The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 or AFS Voltage B2S1 (A/F)	+25%	Rich	Less than 3.1 V
AFS Voltage B1S1 or AFS Voltage B2S1 (A/F)	-12.5%	Lean	More than 3.4 V
O2S B1S2 or O2S B2S2 (HO2)	+25%	Rich	More than 0.55 V
O2S B1S2 or O2S B2S2 (HO2)	-12.5%	Lean	Less than 0.4 V

NOTICE:

The Air Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

Case	A/F Sensor (Sensor 1) Output Voltage	HO2 Sensor (Sensor 2) Output Voltage	Main Suspected Trouble Area
1			-
2			A/F sensor A/F sensor heater A/F sensor circuit
3			HO2 sensor HO2 sensor heater HO2 sensor circuit
4			Injector Fuel pressure Gas leakage from exhaust system (Air fuel ratio extremely rich or lean)

Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.

HINT:

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 A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check for conditions that would cause the engine to run lean.

1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195, P2196, P2197 OR P2198)

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 / Trouble Codes.

Read DTCs.

Result
Display (DTC Output) Proceed to
P2195, P2196, P2197 or P2198 A
P2195, P2196, P2197 or P2198 and other DTCs B
HINT:

If any DTCs other than P2195, P2196, P2197 or P2198 are output, troubleshoot those DTCs first.

Result
Display (DTC Output)	Proceed to
P2195, P2196, P2197 or P2198	A
P2195, P2196, P2197 or P2198 and other DTCs	B

B

GO TO DTC CHART

A

2.READ VALUE USING INTELLIGENT TESTER (TEST VALUE OF A/F SENSOR)

Connect the intelligent tester to the DLC3.

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

Clear DTCs .

Drive the vehicle in accordance with the drive pattern described in the CONFIRMATION DRIVING PATTERN.

Enter the following menus: Powertrain / Engine and ECT / Monitor / O2 Sensor.

Check that the status of O2 Sensor is Complete.

If the status is still Incomplete, drive the vehicle according to the driving pattern again.

Enter the following menus: Powertrain / Engine and ECT / Monitor / O2 Sensor / Details / RANGE B1 S1.

Check the test value of the A/F sensor output current during fuel-cut.

Result
Test Value Proceed to
Within normal range (1.4 mA or more, and less than 3.6 mA) A
Outside normal range (Less than 1.4 mA, or 3.6 mA or more) B

Result
Test Value	Proceed to
Within normal range (1.4 mA or more, and less than 3.6 mA)	A
Outside normal range (Less than 1.4 mA, or 3.6 mA or more)	B

B

Go to step 20

A

3.READ VALUE USING INTELLIGENT TESTER (OUTPUT VOLTAGE OF A/F SENSOR)

Connect the intelligent tester to the DLC3.

Start the engine.

Turn the intelligent tester on.

Warm up the air fuel ratio (A/F) sensor at an engine speed of 2500 rpm for 90 seconds.

Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / Snapshot / AFS Voltage B1S1 or AFS Voltage B2S1 and Engine Speed.

Check the A/F sensor voltage three times, once in each of the following conditions:

Engine idling (check for at least 30 seconds)
Engine running at an engine speed of approximately 2500 rpm (without any sudden changes in engine speed)

Engine speed raised to 4000 rpm and then accelerator pedal quickly released so that the throttle valve is fully closed.

Standard:

Condition	A/F Sensor Voltage Variation	Reference
(1) and (2)	Changes at approximately 3.3 V	Between 3.1 V and 3.5 V
(3)	Increases to 3.8 V or more	This occurs during engine deceleration (when fuel-cut performed)

HINT:

For more information, see the diagrams below.

DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

HINT:

If the output voltage of the A/F sensor remains at approximately 3.3 V (see "Malfunctioning" diagram) under any conditions, including those above, the A/F sensor may have an open circuit. (This will also happen if the A/F sensor heater has an open circuit.)
If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see "Malfunctioning" diagram) under any conditions, including those above, the A/F sensor may have a short circuit.
The ECM stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the A/F sensor output voltage.
The ECM must establish a closed throttle valve position learned value to perform fuel cut. If the battery cable has been disconnected and reconnected, the vehicle must be driven over 16 km/h (10 mph) to allow the ECM to learn the closed throttle valve position.
When the vehicle is driven: The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. For the vehicle, this translates to a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
The A/F sensor is a current output element; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage.

NG

Go to step 10

OK

4.PERFORM CONFIRMATION DRIVING PATTERN

NEXT

5.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198)

Connect the intelligent tester to the DLC3.

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

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

Read the DTCs.

Result
Display (DTC Output) Proceed to
P2195, P2196, P2197 or P2198 A
No output B

Result
Display (DTC Output)	Proceed to
P2195, P2196, P2197 or P2198	A
No output	B

B

Go to step 9

A

6.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor .

NEXT

7.PERFORM CONFIRMATION DRIVING PATTERN

NEXT

8.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198)

Connect the intelligent tester to the DLC3.

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

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

Read DTCs.

Result
Display (DTC Output) Proceed to
No output A
P2195, P2196, P2197 or P2198 B

Result
Display (DTC Output)	Proceed to
No output	A
P2195, P2196, P2197 or P2198	B

B

REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN

A

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

NO

CHECK FOR INTERMITTENT PROBLEMS

YES

DTC CAUSED BY RUNNING OUT OF FUEL

10.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the Air Fuel ratio (A/F) sensor connector. DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

Disconnect the Air Fuel ratio (A/F) sensor connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance:

for Bank 1 Sensor 1
Tester Connection Condition Specified Condition
1 (HA1A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 ?
1 (HA1A) - 4 (A1A-) Always 10 k? or higher
for Bank 2 Sensor 1
Tester Connection Condition Specified Condition
1 (HA2A) - 2 (+B) 20°C (68°F) 1.8 to 3.4 ?
1 (HA2A) - 4 (A2A-) Always 10 k? or higher

NG

REPLACE AIR FUEL RATIO SENSOR

OK

11.INSPECT INTEGRATION RELAY (A/F RELAY)

Remove the integration relay from the engine room relay block. DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

Remove the integration relay from the engine room relay block.

Inspect the A/F fuse.
1. Remove the A/F fuse from the integration relay.
2. Measure the resistance according to the value(s) in the table below.
  
  Standard Resistance:
  
  Tester Connection Condition Specified Condition
  A/F fuse Always Below 1 ?
3. Reinstall the A/F fuse.

Inspect the A/F relay.

Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
1A-4 - 1C-1	Battery voltage not applied to terminals 1A-2 and 1A-3	10 k? or higher
1A-4 - 1C-1	Battery voltage applied to terminals 1A-2 and 1A-3	Below 1 ?

NG

REPLACE INTEGRATION NO.1 RELAY

OK

12.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

Disconnect the ECM connector DTC P2195 P2196 P2197 P2198 Land Cruiser 1GR-FE

Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):

for LHD
Tester Connection	Condition	Specified Condition
C22-1 (HA1A) - C45-86 (HA1A)	Always	Below 1 ?
C23-1 (HA2A) - C45-109 (HA2A)	Always	Below 1 ?

for RHD
Tester Connection	Condition	Specified Condition
C22-1 (HA1A) - C46-86 (HA1A)	Always	Below 1 ?
C23-1 (HA2A) - C46-109 (HA2A)	Always	Below 1 ?

Standard Resistance (Check for Short):

for LHD
Tester Connection	Condition	Specified Condition
C22-1 (HA1A) or C45-86 (HA1A) - Body ground	Always	10 k? or higher
C23-1 (HA2A) or C45-109 (HA2A) - Body ground	Always	10 k? or higher

for RHD
Tester Connection	Condition	Specified Condition
C22-1 (HA1A) or C46-86 (HA1A) - Body ground	Always	10 k? or higher
C23-1 (HA2A) or C46-109 (HA2A) - Body ground	Always	10 k? or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

13.CHECK AIR INDUCTION SYSTEM

Check the air induction system for vacuum leakage.

OK:

No leakage from air induction system.

NG

REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK

14.CHECK FUEL PRESSURE

Check the fuel pressure.

NG

REPAIR OR REPLACE FUEL SYSTEM

OK

15.INSPECT FUEL INJECTOR

Check the injector injection (whether fuel volume is large or small, and whether injection pattern is poor) .

NG

REPLACE FUEL INJECTOR

OK

16.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor .

NEXT

17.PERFORM CONFIRMATION DRIVING PATTERN

NEXT

18.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198)

Connect the intelligent tester to the DLC3.

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

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

Read DTCs.

Result
Display (DTC Output) Proceed to
No output A
P2195, P2196, P2197 or P2198 B

B

REPLACE ECM AND PERFORM CONFIRMATION DRIVING PATTERN

A

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

NO

CHECK FOR INTERMITTENT PROBLEMS

YES

DTC CAUSED BY RUNNING OUT OF FUEL

20.REPLACE AIR FUEL RATIO SENSOR

Replace the air fuel ratio sensor .

NEXT

21.PERFORM CONFIRMATION DRIVING PATTERN

NEXT

22.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195, P2196, P2197 OR P2198)

Connect the intelligent tester to the DLC3.

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

Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.

Read DTCs.

Result
Display (DTC Output) Proceed to
No output A
P2195, P2196, P2197 or P2198 (A/F sensor pending DTCs) B

B

REPLACE ECM

A

END