SFI SYSTEM(w/o Canister Pump Module), Diagnostic DTC:P21951D, P219523, P21961D, 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

Tech Tips

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

The air fuel ratio sensor generates 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.

B008J8KE01
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 (2 trip detection logic).
  • Open or short in air fuel ratio sensor (sensor 1) circuit

  • Air fuel ratio sensor (sensor 1)

  • Intake system

  • Exhaust gas leak

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly (for port injection)

  • Fuel injector assembly (for direct injection)

  • Fuel system

  • ECM

Comes on DTC stored SAE: P2195
P219523 O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1 Signal Stuck Low

Conditions 1 and 2 continue for 5 seconds or more (2 trip detection logic):


  1. Air fuel ratio sensor voltage is higher than 3.8 V.

  2. 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

  • Exhaust gas leak

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly (for port injection)

  • Fuel injector assembly (for direct injection)

  • Fuel system

  • ECM

Comes on DTC stored SAE: 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 (2 trip detection logic).
  • Open or short in air fuel ratio sensor (sensor 1) circuit

  • Air fuel ratio sensor (sensor 1)

  • Intake system

  • Exhaust gas leak

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly (for port injection)

  • Fuel injector assembly (for direct injection)

  • Fuel system

  • ECM

Comes on DTC stored SAE: P2196
P219624 O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 1 Signal Stuck High

Conditions 1 and 2 continue for 5 seconds or more (2 trip detection logic):


  1. Air fuel ratio sensor voltage is less than 2.8 V.

  2. Heated oxygen sensor voltage is less than 0.69 V.


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

  • Air fuel ratio sensor (sensor 1)

  • Intake system

  • Exhaust gas leak

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel injector assembly (for port injection)

  • Fuel injector assembly (for direct injection)

  • Fuel system

  • ECM

Comes on DTC stored SAE: P2196

Tech Tips


  • 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 / 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 output voltage cannot be confirmed without using the GTS.

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

MONITOR DESCRIPTION



B008JMJE03

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

Sensor Voltage Detection Monitor
Time after engine start 30 seconds or more
Air fuel ratio sensor status Activated
Fuel system status Closed-loop
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

CONFIRMATION DRIVING PATTERN

B008IV1E12
B008IUCE07

  1. Connect the GTS to the DLC3.

  2. Turn the engine switch on (IG).

  3. Turn the GTS on.

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

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

  6. Turn the engine switch on (IG) 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 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.

  9. With the shift lever in M [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.

  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].

    Tech Tips

    Fuel-cut is performed when both of the following conditions are met:


    • Accelerator pedal is fully released.

    • Engine speed is 2500 rpm or higher (fuel injection returns at 1400 rpm).

  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.

    Tech Tips


    • 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

    Tech Tips


    • 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

Refer to DTC P003012.

Click here

CAUTION / NOTICE / HINT

Note

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

Tech Tips


  • 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.

  • 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.

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 engine switch on (IG).

    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

      Tech Tips

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


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs
    5. Turn the engine switch off and wait for at least 30 seconds.

    6. Turn the engine switch on (IG) and turn the GTS on.

    7. Start the engine and warm it up.

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

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


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    10. Input the DTC: P21951D, P219523, P21961D or P219624.

    11. 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
    B
  4. READ VALUE USING GTS (A/F (O2) CURRENT B1S1)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    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) 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.

      Tech Tips


      • 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
    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 air fuel ratio sensor at an engine speed of 2500 rpm for 90 seconds.

    5. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / Data List / 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 output voltages of the air fuel ratio and heated oxygen sensors (A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2) displayed on the GTS.

      Tech Tips


      • 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.

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

      • Rich: During the Control the Injection Volume for A/F Sensor Active Test, 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 the Control the Injection Volume for A/F Sensor Active Test, the output voltage of the heated oxygen sensor alternates correctly.

      Tech Tips

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

      Click here


    B
    A
  6. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks.

      Click here

      OK
      No leaks in the intake system.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  7. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    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
    OK
  9. INSPECT FUEL INJECTOR ASSEMBLY (FOR PORT INJECTION)


    1. Inspect the fuel injector assembly (for port injection) (whether fuel volume is high or low, and whether injection pattern is poor).

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the fuel injector assembly (for port injection).

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  10. READ VALUE USING GTS (FUEL PRESSURE (HIGH))


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

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


      Powertrain > Engine > Data List
      Tester Display
      Fuel Pressure (High)
    5. Read the values.

      Standard
      3000 rpm
      4000 to 8000 kPag.

      Tech Tips

      The A/C switch and all accessory switches should be off, and the shift lever should be in the N or P position, and the engine should be fully warmed up.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  11. INSPECT FUEL INJECTOR ASSEMBLY (FOR DIRECT INJECTION)


    1. Inspect the fuel injector assembly (for direct injection).

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the fuel injector assembly (for direct injection).

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  12. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor.

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      NEXT

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


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs
    5. Turn the engine switch off and wait for at least 30 seconds.

    6. Turn the engine switch on (IG) and turn the GTS on.

    7. Start the engine and warm it up.

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

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


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    10. Input the DTC: P21951D, P219523, P21961D or P219624.

    11. 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

    A
    B
  14. CHECK FUEL LINE


    1. Check the fuel lines for leaks or blockage.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK
    NG
  15. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor.

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      NEXT

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


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs
    5. Turn the engine switch off and wait for at least 30 seconds.

    6. Turn the engine switch on (IG) and turn the GTS on.

    7. Start the engine and warm it up.

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

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


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    10. Input the DTC: P21951D, P219523, P21961D or P219624.

    11. 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
    B