SFI SYSTEM (w/o EGR 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 either of these DTCs is 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 power switch is turned off.

  • Although the DTC titles say the 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 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.

    A01JB8VE01
DTC No. DTC Detection Condition Trouble Area
P0031 Air fuel ratio sensor heater current is below 0.8 A, even when the air fuel ratio sensor heater duty cycle is 30% or more (1 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P0032 An air fuel ratio sensor heater current reaches the high limit (Hybrid IC high current limiter input "Fail") (1 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • ECM
P101D The heater current is higher than the specified value 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.

  • 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.

  • 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.

PROCEDURE


  1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. Inspect the air fuel ratio sensor Click here.


    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

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


    1. A01JCK7E03
      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 power switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D24-2 (+B) - Body ground Power switch on (IG) 11 to 14 V

    4. Reconnect the air fuel ratio sensor connector.


    NG

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

    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
      D24-1 (HA1A) - D28-18 (HA1A) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D24-1 (HA1A) or D28-18 (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 power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Put the engine in inspection mode (maintenance mode) Click here.

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

    7. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed for 2500 rpm for 1 minute.

      Tech Tips

      During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charging control has completed.

    8. Idle the engine for 5 minutes or more.

    9. Enter the following menus: Powertrain / Engine and ECT / DTC.

    10. 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