SFI SYSTEM, Diagnostic DTC:P0031, P0032, P101D

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)
P101D A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON

DESCRIPTION

Refer to DTC P2195 Click here.

Tech Tips


  • When any of these DTCs is set, 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 the oxygen sensor, these DTCs relate to the air fuel ratio sensor.

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

    A019MGDE01
DTC No. DTC Detection Condition Trouble Area
P0031

Air fuel ratio sensor heater current less than 0.8 A

(1 trip detection logic)

  • Open in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor (bank 1 sensor 1)

  • Integration relay (EFI MAIN No. 2 relay)

  • ECM
P0032

Air fuel ratio sensor heater current fail

(1 trip detection logic)

  • Short in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor (bank 1 sensor 1)

  • Integration relay (EFI MAIN No. 2 relay)

  • ECM
P101D The heater current is at the specified value or higher while the heater is not operating (1 trip detection logic) ECM

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Note

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

Tech Tips


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

  • 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 intelligent tester. 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.

  • Change the fuel injection volume using the Control the Injection Volume 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.

PROCEDURE


  1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. A019N7XE15
      Text in Illustration
      *a

      Component without harness connected

      (Air Fuel Ratio Sensor)

      Disconnect the air fuel ratio sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (HA1A) - 2 (+B) 20°C (68°F) 1.6 to 3.2 Ω
      1 (HA1A) - 4 (A1A-) Always 10 kΩ or higher

    3. Reconnect the air fuel ratio sensor connector.


    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE)


    1. A019N7GE30
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor)

      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 Condition Specified Condition
      D20-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V

    4. Reconnect the air fuel ratio sensor connector.


    NG

    INSPECT INTEGRATION RELAY (EFI MAIN NO. 2 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 (Check for Open)
      Tester Connection Condition Specified Condition
      D20-1 (HA1A) - D44-18 (HA1A) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D20-1 (HA1A) or D44-18 (HA1A) - Body ground Always 10 kΩ or higher

    4. Reconnect the air fuel ratio sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

    OK

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032 OR P101D)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Start the engine and idle it for 5 minutes or more.

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

    7. Idle the engine for 5 minutes or more.

    8. Enter the following menus: Powertrain / Engine / DTC.

    9. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0031, P0032 or P101D is output B

    B

    REPLACE ECM Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  5. INSPECT INTEGRATION RELAY (EFI MAIN NO. 2 RELAY)


    1. Inspect the integration relay (EFI MAIN No. 2 relay) Click here.


    NG

    REPLACE INTEGRATION RELAY (EFI MAIN NO. 2 RELAY) Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - BODY GROUND)


    1. Remove the integration relay from the engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3A-1 - Body ground Engine switch on (IG) 11 to 14 V

    3. Reinstall the integration relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - INTEGRATION RELAY)

    OK

  7. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - AIR FUEL RATIO SENSOR)


    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the integration relay from the engine room relay block and junction block assembly.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      3C-2 - D20-2 (+B) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      3C-2 - D20-2 (+B) - Body ground Always 10 kΩ or higher

    4. Reconnect the air fuel ratio sensor connector.

    5. Reinstall the integration relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY - AIR FUEL RATIO SENSOR)

    OK

  8. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - EFI MAIN RELAY)


    1. Remove the integration relay from the engine room relay block and junction block assembly.

    2. Remove the EFI MAIN relay from the engine room relay block and junction block assembly.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      3C-7 - 3 (EFI MAIN relay terminal) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      3C-7 - 3 (EFI MAIN relay terminal) - Body ground Always 10 kΩ or higher

    4. Reinstall the integration relay.

    5. Reinstall the EFI MAIN relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY - EFI MAIN RELAY)

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY - BODY GROUND)