SFI SYSTEM(w/o Canister Pump Module), Diagnostic DTC:P0031, P0032, P0051, P0052, P101D, P103D

DTC Code DTC Name
P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)
P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)
P0051 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 2 Sensor 1)
P0052 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 2 Sensor 1)
P101D A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON
P103D A/F Sensor Heater Circuit Performance Bank 2 Sensor 1 Stuck ON

DESCRIPTION

Refer to DTC P2195.

Click here

Tech Tips


  • When any of these DTCs are stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor heater in fail-safe mode. Fail-safe mode continues until the engine switch is turned off.

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

  • The ECM has a pulse width modulated control circuit to adjust the current through the heater. The air fuel ratio sensor heater circuit uses a relay on the +B side of the circuit.

    B000X57E02
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) Air fuel ratio sensor heater current is less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 10% or higher (1 trip detection logic).

  • Open in air fuel ratio sensor (bank 1 sensor 1) heater circuit

  • Air fuel ratio sensor (bank 1 sensor 1)

  • A/F HTR relay

  • ECM

 Comes on DTC stored
P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1) Air fuel ratio sensor heater current reaches the high limit (1 trip detection logic).

  • Short in air fuel ratio sensor (bank 1 sensor 1) heater circuit

  • Air fuel ratio sensor (bank 1 sensor 1)

  • A/F HTR relay

  • ECM

 Comes on DTC stored
P0051 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 2 Sensor 1) Air fuel ratio sensor heater current is less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 10% or higher (1 trip detection logic).

  • Open in air fuel ratio sensor (bank 2 sensor 1) heater circuit

  • Air fuel ratio sensor (bank 2 sensor 1)

  • A/F HTR relay

  • ECM

 Comes on DTC stored
P0052 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 2 Sensor 1) Air fuel ratio sensor heater current reaches the high limit (1 trip detection logic).

  • Short in air fuel ratio sensor (bank 2 sensor 1) heater circuit

  • Air fuel ratio sensor (bank 2 sensor 1)

  • A/F HTR relay

  • ECM

 Comes on DTC stored
P101D A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON Air fuel ratio sensor heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

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

  • ECM

 Comes on DTC stored
P103D A/F Sensor Heater Circuit Performance Bank 2 Sensor 1 Stuck ON Air fuel ratio sensor heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

  • Open or short in air fuel ratio sensor (bank 2 sensor 1) heater circuit

  • ECM

 Comes on DTC stored

MONITOR DESCRIPTION

The ECM uses information from the air fuel ratio sensor to regulate the air fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the three-way catalytic converter to purify the exhaust gases.

The air fuel ratio sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum-coated zirconia and includes an integrated heating element.

The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.

The air fuel ratio sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the air fuel ratio sensor becomes inaccurate. As a result, the ECM is unable to regulate the air fuel ratio properly.

When the current in the air fuel ratio sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.

MONITOR STRATEGY

Frequency of Operation Continuous

TYPICAL ENABLING CONDITIONS

P0031 and P0051
Output duty cycle 10% or higher
P0032 and P0052
Output duty cycle Higher than 0%
P101D and P103D
Output duty cycle Less than 60%

CONFIRMATION DRIVING PATTERN

B000Y9QE01

  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).

  7. Turn the GTS on [A].

  8. Start the engine and idle it for 5 minutes or more [B].

  9. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].

  10. Idle the engine for 5 minutes or more [D].

  11. Enter the following menus: Powertrain / Engine / Trouble Codes [E].

  12. 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.

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

  14. Input the DTC: P0031, P0032, P0051, P0052, P101D or P103D.

  15. 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 [E] again.

WIRING DIAGRAM

Refer to DTC P2195.

Click here

CAUTION / NOTICE / HINT

Note

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

Tech Tips


  • Refer to "Data List / Active Test" [A/F Heater Duty #1 and A/F Heater Duty #2].

    Click here

  • Bank 1 refers to the bank that includes the No. 1 cylinder*.

    *: The No. 1 cylinder is the cylinder which is farthest from the transmission.

  • Bank 2 refers to the bank that does not include the No. 1 cylinder.

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

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

  • Change the fuel injection volume using the Control the Injection Volume for A/F Sensor function provided in the Active Test and monitor the air fuel ratio sensor output voltage Click here. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

  • 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. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. Inspect 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
      OK
      NG

    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR)

    B000XM9C55
    *a

    Front view of wire harness connector

    (to Air Fuel Ratio Sensor)
    *b Bank 1
    *c Bank 2

    1. Disconnect the air fuel ratio sensor connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G62-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      G63-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - A/F HTR RELAY) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)


    1. Disconnect the air fuel ratio sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G62-1 (HA1A) - G42-19 (HA1A) Always Below 1 Ω
      G63-1 (HA2A) - G42-18 (HA2A) Always Below 1 Ω
      G62-1 (HA1A) or G42-19 (HA1A) - Body ground and other terminals Always 10 kΩ or higher
      G63-1 (HA2A) or G42-18 (HA2A) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CLEAR DTC


    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.

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032, P0051, P0052, P101D AND P103D)


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

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


      Powertrain > Engine > Trouble Codes

    3. Read the pending DTCs.

      Result
      Result Proceed to
      DTCs are not output A
      DTC P0031, P0032, P0051, P0052, P101D and/or P103D is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here

  6. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - A/F HTR RELAY)


    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the A/F HTR relay from the No. 1 engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G62-2 (+B) - 3 (A/F HTR relay holder) Always Below 1 Ω
      G63-2 (+B) - 3 (A/F HTR relay holder) Always Below 1 Ω
      G62-2 (+B) or 3 (A/F HTR relay holder) - Body ground and other terminals Always 10 kΩ or higher
      G63-2 (+B) or 3 (A/F HTR relay hplder) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. INSPECT A/F HTR RELAY


    1. Inspect the A/F HTR relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE A/F HTR RELAY

    OK

  8. CHECK TERMINAL VOLTAGE (POWER SOURCE OF A/F HTR RELAY)


    1. Remove the A/F HTR relay from the No. 1 engine room relay block and junction block assembly.

      B000WFSC01
      *A for LHD *B for RHD
      *1 No. 1 Engine Room Relay Block and Junction Block Assembly *2 A/F HTR Relay

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      5 (A/F HTR relay holder) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F HTR RELAY - AUXILIARY BATTERY)

    OK

  9. CHECK HARNESS AND CONNECTOR (A/F HTR RELAY - BODY GROUND)


    1. Remove the A/F HTR relay from the No. 1 engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (A/F HTR relay holder) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F HTR RELAY - EFI-MAIN NO. 1 RELAY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR