SFI SYSTEM, Diagnostic DTC:P21951D,P219523,P21961D and P219624

DTC Code DTC Name
P21951D O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Circuit Current Out of Range
P219523 O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Signal Stuck Low
P21961D O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1 Circuit Current Out of Range
P219624 O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1 Signal Stuck High

DESCRIPTION

Tip:

Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.

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 level, and regulates the fuel injection duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type and 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 a narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore 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.

A363544E01

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

Note

P21951D

O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Circuit Current Out of Range

While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is 2.2 mA or higher for 3 seconds or more (2 trip detection logic).

  • Air fuel ratio sensor (sensor 1)

  • ECM

Comes on

DTC stored

SAE Code:

P2195

P219523

O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Signal Stuck Low

Both of the following conditions are met 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)

  • Intake system

  • Gas leak from exhaust system

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly

  • Fuel system

  • ECM

Comes on

DTC stored

SAE Code:

P2195

P21961D

O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1 Circuit Current Out of Range

While the fuel-cut operation is performed (during vehicle deceleration), the air fuel ratio sensor current is less than 0.47 mA for 3 seconds or more (2 trip detection logic).

  • Air fuel ratio sensor (sensor 1)

  • ECM

Comes on

DTC stored

SAE Code:

P2196

P219624

O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1 Signal Stuck High

Both of the following conditions are met for 5 seconds or more (2 trip detection logic):

(a) Air fuel ratio sensor voltage is less than 2.8 V.

(b) Heated oxygen sensor voltage is less than 0.66 V.

  • Open or short in air fuel ratio sensor (sensor 1) circuit

  • Air fuel ratio sensor (sensor 1)

  • Intake system

  • Gas leak from exhaust system

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly

  • Fuel system

  • ECM

Comes on

DTC stored

SAE Code:

P2196
Tip:

  • When any of these DTCs are stored, check the air fuel ratio sensor voltage output by entering the following menus on the GTS: Powertrain / Engine / Data List / All Data / A/F (O2) Sensor Voltage B1S1.

  • Short-term fuel trim values can also be read using the GTS.

  • 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 GTS.

  • If an air fuel ratio sensor malfunction is detected, the ECM will store a DTC.

MONITOR DESCRIPTION

Sensor Voltage Detection Monitor

Under air fuel ratio feedback control, If the air fuel ratio sensor output voltage is less than 2.8 V (very rich condition) for 5 seconds despite the heated oxygen sensor output voltage being less than 0.66 V, the ECM stores DTC P219624. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the heated oxygen sensor output voltage being 0.21 V or higher, DTC P219523 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 3 seconds or more of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and stores DTC P21951D (stuck on high side). If the air fuel ratio sensor output is less than 0.47 mA for 3 seconds or more of cumulative time, the ECM stores DTC P21961D (stuck on low side).

A283591E02

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

Once per driving cycle: Sensor current detection monitor

Duration

3 seconds: Sensor current detection monitor

5 seconds: Sensor voltage detection monitor

TYPICAL ENABLING CONDITIONS

Table 1. Sensor Voltage Detection Monitor

Time after engine start

30 seconds or more

Fuel system status

Closed loop
Table 2. Sensor Current Detection Monitor

Battery voltage

11 V or higher

Engine coolant temperature

75°C (167°F) or higher

Atmospheric pressure

76 kPa(abs) [11.02 psi(abs)] or higher

Air fuel ratio sensor status

Activated

Continuous time of fuel-cut

3 seconds to 10 seconds

TYPICAL MALFUNCTION THRESHOLDS

Table 3. P219523: Sensor Voltage Detection Monitor (Lean Side Malfunction)

Heated oxygen sensor voltage

0.21 V or higher

Air fuel ratio sensor voltage

Higher than 3.8 V
Table 4. P219624: Sensor Voltage Detection Monitor (Rich Side Malfunction)

Heated oxygen sensor voltage

Less than 0.66 V

Air fuel ratio sensor voltage

Less than 2.8 V
Table 5. P21951D: Sensor Current Detection Monitor (High Side Malfunction)

Air fuel ratio sensor current

2.2 mA or higher
Table 6. P21961D: Sensor Current Detection Monitor (Low Side Malfunction)

Air fuel ratio sensor current

Less than 0.47 mA

CONFIRMATION DRIVING PATTERN

A283818E24
A268862E07

  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON.

  3. Turn the GTS on.

  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

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

  6. Turn the ignition switch to ON and turn the GTS on.

  7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [A].

  8. Drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for at least 10 minutes [B].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

  9. With shift state M selected (CVT models) or second gear (M/T models) [C], accelerate the vehicle to 75 km/h (47 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.

  10. 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].

  11. Allow the vehicle to decelerate until the vehicle speed decreases to less than 10 km/h (6 mph).

  12. Repeat steps [C] through [E] above at least 3 times in one driving cycle.

  13. Enter the following menus: Powertrain / Engine / Trouble Codes [F].

  14. Read the pending DTCs.

    Tip:

    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

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

  16. Input the DTC: P21951D, P219523, P21961D or P219624.

  17. 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

    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
    Tip:

    • 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.

WIRING DIAGRAM

A357472E01

CAUTION / NOTICE / HINT

Note:

Inspect the fuses for circuits related to this system before performing the following procedure.

Tip:

  • Sensor 1 refers to the sensor closest to the engine assembly.

  • Sensor 2 refers to the sensor farthest away from the engine assembly.

  • 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.

  • 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

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P21951D, P219523, P21961D OR P219624)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Trouble Codes.

    5. Read the DTCs.

      Powertrain > Engine > Trouble Codes

      Result

      Result

      Proceed to

      DTC P21951D, P219523, P21961D or P219624 is output

      A

      DTC P21951D, P219523, P21961D or P219624 and P013613, P013617 or P01361C are output

      DTC P21951D, P219523, P21961D or P219624 and other DTCs are output

      B
      Tip:

      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.

    B

    GO TO DTC CHART

    Click hereClick here

    A

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

    1. Has the vehicle run out of fuel in the past?

    Result

    Proceed to

    YES

    NO
    NO

    READ VALUE USING GTS (A/F (O2) SENSOR CURRENT B1S1)Click here

    YES

  3. CHECK WHETHER DTC OUTPUT RECURS (DTC P21951D, P219523, P21961D OR P219624)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

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

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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

      Powertrain > Engine > Utility

      Tester Display

      All Readiness

    11. Input the DTC: P21951D, P219523, P21961D or P219624.

    12. Check the DTC judgment.

      Result

      Result

      Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P21951D, P219523, P21961D or P219624 is output)

      B
    A

    DTC CAUSED BY RUNNING OUT OF FUEL

    B

  4. READ VALUE USING GTS (A/F (O2) SENSOR CURRENT B1S1)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

    5. Enter the following menus: Powertrain / Engine / Data List / All Data / A/F (O2) Sensor Current B1S1.

      Powertrain > Engine > Data List

      Tester Display

      A/F (O2) Sensor Current B1S1

    6. Check the test value of the air fuel ratio sensor output current during fuel-cut, referring to the Driving Pattern Detail for [C] through [E] in the Confirmation Driving Pattern.

      Tip:

      • To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.

      • If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.

      Result

      Test Value

      Proceed to

      Within normal range

      (0.47 mA or higher, and less than 2.2 mA)

      A

      Outside normal range

      (less than 0.47 mA, or 2.2 mA or higher)

      B
    B

    REPLACE AIR FUEL RATIO SENSORClick here

    A

  5. PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)

    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.

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

      Powertrain > Engine > Active Test

      Active Test Display

      Control the Injection Volume for A/F Sensor

      Data List Display

      A/F (O2) Sensor Voltage B1S1

      O2 Sensor Voltage B1S2

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

    7. Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2) displayed on the GTS.

      Tip:

      • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.

      • 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.

      Table 7. Standard

      GTS Display (Sensor)

      Injection Volume

      Status

      Voltage

      A/F (O2) Sensor Voltage B1S1

      (Air fuel ratio)

      12.5%

      Rich

      Below 3.1 V

      -12.5%

      Lean

      Higher than 3.4 V

      O2 Sensor Voltage B1S2

      (Heated oxygen)

      12.5%

      Rich

      Higher than 0.55 V

      -12.5%

      Lean

      Below 0.4 V

      Result

      Status of A/F (O2) Sensor Voltage B1S1

      Status of O2 Sensor Voltage 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

      Lean

      Lean/Rich

      Air fuel ratio sensor malfunction

      B

      Rich

      Lean/Rich

      Air fuel ratio sensor malfunction

      Lean/Rich

      Lean/Rich

      Normal

      • Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently below 0.4 V.

      • Rich: During Control the Injection Volume for A/F Sensor, the A/F (O2) Sensor Voltage B1S1 is consistently below 3.1 V, and the O2 Sensor Voltage B1S2 is consistently higher than 0.55 V.

      • Lean/Rich: During Control the Injection Volume for A/F Sensor, the output voltage of the air fuel ratio sensor or heated oxygen sensor alternates correctly.

        Tip:

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

        Click here

    B

    REPLACE AIR FUEL RATIO SENSORClick here

    A

  6. CHECK INTAKE SYSTEM

    1. Check the intake system for vacuum leaks.

      Click here

      OK

      No leaks in the intake system.

      Tip:

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  7. CHECK FOR EXHAUST GAS LEAK

    1. Check for exhaust gas leaks.

      OK

      No gas leaks.

      Tip:

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE EXHAUST SYSTEM

    OK

  8. CHECK FUEL PRESSURE (FOR LOW PRESSURE SIDE)

    1. Check the fuel pressure (for low pressure side).

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    INSPECT FUEL PUMP (FOR LOW PRESSURE SIDE)Click here

    OK

  9. READ VALUE USING GTS (FUEL PRESSURE (HIGH))

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Start the engine and warm it up.

    5. Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Pressure (High).

      Powertrain > Engine > Data List

      Tester Display

      Fuel Pressure (High)

    6. Read the values.

      Standard

      GTS Display

      Condition

      Specified Condition

      Fuel Pressure (High)

      Shift lever position: P or neutral

      A/C: Off

      Engine idling

      4000 to 18000 kPag

      Shift lever position: P or neutral

      A/C: Off

      Engine speed: 3000 rpm

      8000 to 18000 kPag

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE FUEL SYSTEM (FOR HIGH PRESSURE SIDE)

    OK

  10. INSPECT FUEL INJECTOR ASSEMBLY

    1. Inspect the fuel injector assembly.

      Click here

      Tip:

      Perform "Inspection After Repair" after replacing the fuel injector assembly.

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE FUEL INJECTOR ASSEMBLY

    Click here

    OK

  11. REPLACE AIR FUEL RATIO SENSOR

    1. Replace the air fuel ratio sensor.

      Click here

      Tip:

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

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  12. CHECK WHETHER DTC OUTPUT RECURS (DTC P21951D, P219523, P21961D OR P219624)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

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

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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

      Powertrain > Engine > Utility

      Tester Display

      All Readiness

    11. Input the DTC: P21951D, P219523, P21961D or P219624.

    12. Check the DTC judgment result.

      Result

      Result

      Proceed to

      ABNORMAL

      (DTC P21951D, P219523, P21961D or P219624 is output)

      A

      NORMAL

      (DTCs are not output)

      B
    B

    END

    A

  13. REPLACE ECM

    1. Replace the ECM.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  14. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

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

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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

      Powertrain > Engine > Utility

      Tester Display

      All Readiness

    11. Input the DTC: P21951D, P219523, P21961D or P219624.

    12. Check the DTC judgment result.

      Table 8. 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

      N/A

      • Unable to perform DTC judgment

      • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Result

    Proceed to

    NEXT
    NEXT

    END

  15. INSPECT FUEL PUMP (FOR LOW PRESSURE SIDE)

    1. Inspect the fuel pump (for low pressure side).

      Click here

      Tip:

      Perform "Inspection After Repair" after replacing the fuel pump (for low pressure side).

      Click here

    Result

    Proceed to

    OK

    NG
    OK

    REPAIR OR REPLACE FUEL LINE (FOR LOW PRESSURE SIDE)

    NG

    REPLACE FUEL PUMP (FOR LOW PRESSURE SIDE)

    Click hereClick here

  16. REPLACE AIR FUEL RATIO SENSOR

    1. Replace the air fuel ratio sensor.

      Click here

      Tip:

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

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  17. CHECK WHETHER DTC OUTPUT RECURS (DTC P21951D, P219523, P21961D OR P219624)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs

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

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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

      Powertrain > Engine > Utility

      Tester Display

      All Readiness

    11. Input the DTC: P21951D, P219523, P21961D or P219624.

    12. Check the DTC judgment result.

      Result

      Result

      Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P21951D, P219523, P21961D or P219624 is output)

      B
    A

    END

    B

    REPLACE ECM

    Click here