TYPICAL MALFUNCTION THRESHOLDS
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196)
CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
READ VALUE USING TECHSTREAM (TEST VALUE OF AIR FUEL RATIO SENSOR)
READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF AIR FUEL RATIO SENSOR)
INSPECT FUEL INJECTOR ASSEMBLY
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED
CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196)
DTC P2195 Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1) |
DTC P2196 Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1) |
DESCRIPTION
- 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 and located near the engine assembly.
The air fuel ratio sensor is the planar type and is integrated with the 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, and 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 three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
*: 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.

DTC No. | DTC Detection Condition | Trouble Area |
P2195 | Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic)
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While fuel-cut operation performed (during vehicle deceleration), air fuel ratio sensor current is 2.2 mA or more for 3 seconds (2 trip detection logic) |
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P2196 | Conditions (a) and (b) continue for 5 seconds or more (2 trip detection logic)
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While fuel-cut operation performed (during vehicle deceleration), air fuel ratio sensor current is less than 0.7 mA for 3 seconds (2 trip detection logic) |
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- HINT:
- When any of these DTCs is stored, check the air fuel ratio sensor voltage output by entering the following menus on the Techstream: Powertrain / Engine and ECT / Data List / AFS Voltage B1S1.
- Short-term fuel trim values can also be read using the Techstream.
- The ECM regulates the voltages at the A1A+ and A1A- terminals of the ECM to a constant level. Therefore, the air fuel ratio sensor voltage output cannot be confirmed without using the Techstream.
- If an air fuel ratio sensor malfunction is detected, the ECM stores a DTC.
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 0.69 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.
- Sensor Current Detection Monitor
A rich air fuel mixture causes a low air fuel ratio sensor current, and a lean air fuel mixture causes a high air fuel ratio sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The ECM monitors the air fuel ratio sensor current during fuel-cut and detects any abnormal current values.
If the air fuel ratio sensor output is 2.2 mA or higher for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and stores DTC P2195 (stuck on high side). If the air fuel ratio sensor output is below 0.7 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 (stuck on low side).

MONITOR STRATEGY
Related DTCs | P2195: Air Fuel Ratio Sensor (Bank 1 Sensor 1) Signal Stuck Lean P2196: Air Fuel Ratio Sensor (Bank 1 Sensor 1) Signal Stuck Rich |
Required Sensors/Components (Main) | Air fuel ratio sensor |
Required Sensors/Components (Related) | Heated oxygen sensor |
Frequency of Operation | Continuous: Sensor voltage detection monitor Once per driving cycle: Sensor current detection monitor |
Duration | 5 seconds: Sensor voltage detection monitor 3 seconds: Sensor current detection monitor |
MIL Operation | 2 driving cycles |
Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
Monitor runs whenever following DTCs not present | P0016 (VVT System - Misalignment) P0031, P0032, P101D (Air Fuel Ratio Sensor Heater) P0102, P0103 (Mass Air Flow Sensor) P0112, P0113 (Intake Air Temperature Sensor) P0115, P0117, P0118 (Engine Coolant Temperature Sensor) P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control) P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle Position Sensor) P0128 (Thermostat) P0171, P0172 (Fuel System) P0301 - P0304 (Misfire) P0335 (Crankshaft Position Sensor) P0340 (Camshaft Position Sensor) P0451, P0452, P0453 (EVAP System) P0500 (Vehicle Speed Sensor) P0505 (IAC Valve) P219A (Air Fuel Ratio Imbalance) |
Time after engine start | 30 seconds or more |
Fuel system status | Closed loop |
Air fuel ratio sensor status | Activated |
Battery voltage | 11 V or higher |
Atmospheric pressure | 76 kPa(abs) [570 mmHg(abs)] or higher |
Air fuel ratio sensor status | Activated |
Engine coolant temperature | 75°C (167°F) or higher |
Continuous time of fuel cut | 3 to 10 seconds |
TYPICAL MALFUNCTION THRESHOLDS
Rear heated oxygen sensor voltage | 0.21 V or higher |
Air fuel ratio sensor voltage | Higher than 3.8 V |
Rear heated oxygen sensor voltage | Below 0.69 V |
Air fuel ratio sensor voltage | Below 2.8 V |
Air fuel ratio sensor current | 2.2 mA or higher |
Air fuel ratio sensor current | Below 0.7 mA |
MONITOR RESULT
Refer to detailed information in Checking Monitor Status (YARIS_NCP93 RM000000PDR0B4X.html).Monitor ID | Test ID | Scaling | Unit | Description |
$01 | $91 | Multiply by 0.004 | mA | A/F sensor current |
CONFIRMATION DRIVING PATTERN


- Connect the Techstream to the DLC3.
- Turn the ignition switch to ON.
- Turn the Techstream 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 Techstream on.
- Start the engine and warm it up until the ECT reaches 75°C (167°F) or higher [A].
- On the Techstream, enter the following menus to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut.
- Drive the vehicle at a speed between 60 and 120 km/h (37 and 75 mph) for at least 10 minutes [B].
- CAUTION:
- When performing the confirmation driving pattern, obey all speed limits and traffic laws.
- Shift the transaxle to 3rd gear (for manual transaxle) or 3 position (for automatic transaxle) [C].
- Accelerate the vehicle to 64 km/h (40 mph) or more by depressing the accelerator pedal for at least 10 seconds [D].
- CAUTION:
- When performing the confirmation driving pattern, obey all speed limits and traffic laws.
- Soon after performing step [D] above, release the accelerator pedal for at least 4 seconds without depressing the brake pedal in order to execute fuel-cut control [E].
- HINT:
- Fuel-cut is performed when the following conditions are met:
- Accelerator pedal is fully released.
- Engine speed is 2500 rpm or more (fuel injection returns at 1000 rpm).
- Allow the vehicle to decelerate until the vehicle speed decreases to less than 10 km/h (6.25 mph).
- Repeat steps [C] through [E] above at least 3 times in one driving cycle.
- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [F].
- Read 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 and ECT / Utility / All Readiness.
- Input the DTC: P2195 or P2196.
- Check the DTC judgment result.
Techstream 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 steps [B] through [F] again.
- DTC judgment completed
- If no pending DTC is output, perform a universal trip and check for permanent DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
- HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
WIRING DIAGRAM
Refer to DTC P0031 (YARIS_NCP93 RM000000WC10MFX_07.html).INSPECTION PROCEDURE
- NOTICE:
- Inspect the fuses for circuits related to this system before performing the following inspection procedure.
- HINT:
- 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 Techstream. 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.
- 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.
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P2195 OR P2196) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Read DTCs.
Result Result Proceed to DTC P2195 or P2196 is output A DTC P2195 or P2196 and P0136, P0137 or P0138 are output DTC 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.
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A | |
2.CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST |
Has the vehicle run out of fuel in the past?
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YES | |
3.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
Turn the Techstream 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 Proceed to NORMAL (DTC is not output) A ABNORMAL (DTC P2195 or P2196 is output) B
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A | ||
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4.READ VALUE USING TECHSTREAM (TEST VALUE OF AIR FUEL RATIO SENSOR) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
Enter the following menus: Powertrain / Engine and ECT / Monitor / Current Monitor / O2 Sensor / Current.
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 / Current Monitor / O2 Sensor / Details / RANGE B1S1.
Check the test value of the air fuel ratio sensor output current during fuel-cut.
Result Result Proceed to Within normal range (0.7 mA or higher, and lower than 2.2 mA) A Outside normal range (lower than 0.7 mA, or 2.2 mA or higher) B
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A | |
5.READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF AIR FUEL RATIO SENSOR) |
Connect the Techstream to the DLC3.
Start the engine.
Turn the Techstream 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.
Perform the Control the Injection Volume 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 Techstream.
- HINT:
- Change the fuel injection volume within the range of -12% to +12%. 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.
Techstream Display (Sensor) Injection Volume Status Voltage AFS Voltage B1S1
(Air fuel ratio)+12% Rich Below 3.1 V AFS Voltage B1S1
(Air fuel ratio)-12% Lean Higher than 3.4 V O2S B1S2
(Heated oxygen)+12% Rich Higher than 0.55 V O2S B1S2
(Heated oxygen)-12% 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 Active Test, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.
- Rich: During the Control the Injection Volume Active Test, the AFS Voltage B1S1 is consistently below 3.1 V, and the O2S B1S2 is consistently higher than 0.55 V.
- Lean/Rich: During the Control the Injection Volume 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] (YARIS_NCP93 RM000000SXS05AX.html).
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A | |
6.CHECK INTAKE SYSTEM |
Check the intake system for vacuum leaks (YARIS_NCP93 RM000004VL8003X.html).
- OK:
- No leaks in the intake system.
- HINT:
- Perform "Inspection After Repair" after repairing or replacing the intake system (YARIS_NCP93 RM000004NJD006X.html).
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OK | |
7.CHECK FOR EXHAUST GAS LEAK |
Check for exhaust gas leaks.
- OK:
- No gas leaks.
- HINT:
- Perform "Inspection After Repair" after repairing or replacing the exhaust system (YARIS_NCP93 RM000004NJD006X.html).
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OK | |
8.CHECK FUEL PRESSURE |
Check the fuel pressure (YARIS_NCP93 RM000001IQZ080X_01_0002.html).
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OK | |
9.INSPECT FUEL INJECTOR ASSEMBLY |
Check the fuel injector assembly injection (whether fuel volume is high or low, and whether injection pattern is poor) (YARIS_NCP93 RM000001EDQ04MX.html).
- HINT:
- Perform "Inspection After Repair" after replacing the fuel injector assembly (YARIS_NCP93 RM000004NJD006X.html).
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OK | |
10.REPLACE AIR FUEL RATIO SENSOR |
Replace the air fuel ratio sensor (YARIS_NCP93 RM000003VIL00HX.html).
- HINT:
- Perform "Inspection After Repair" after replacing the air fuel ratio sensor (YARIS_NCP93 RM000004NJD006X.html).
NEXT | |
11.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
Turn the Techstream 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 Proceed to ABNORMAL (DTC P2195 or P2196 is output) A NORMAL (DTC is not output) B
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A | |
12.REPLACE ECM |
Replace the ECM (YARIS_NCP93 RM000001CN002IX.html).
NEXT | |
13.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
Turn the Techstream 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 Techstream 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
- DTC judgment completed
NEXT | ||
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14.REPLACE AIR FUEL RATIO SENSOR |
Replace the air fuel ratio sensor (YARIS_NCP93 RM000003VIL00HX.html).
- HINT:
- Perform "Inspection After Repair" after replacing the air fuel ratio sensor (YARIS_NCP93 RM000004NJD006X.html).
NEXT | |
15.CHECK WHETHER DTC OUTPUT RECURS (DTC P2195 OR P2196) |
Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Clear the DTCs (YARIS_NCP93 RM000000PDK0T5X.html).
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON.
Turn the Techstream 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 Proceed to NORMAL (DTC is not output) A ABNORMAL (DTC P2195 or P2196 is output) B
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A | ||
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16.CHECK FUEL LINE |
Check the fuel lines for leaks or blockage.
- HINT:
- Perform "Inspection After Repair" after replacing the fuel pump (YARIS_NCP93 RM000004NJD006X.html).
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OK | ||
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