SFI SYSTEM, Diagnostic DTC:P0031,P0032 and 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).

Tip:
  • Although the DTC titles say 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.

  • When either of these DTCs is stored, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.

  • The ECM provides a pulse width modulated signal to the 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.

    A157557E43

DTC No.

DTC Detection Condition

Trouble Area

P0031

The air fuel Ratio (A/F) sensor heater current is less than 0.8 A (1 trip detection logic).

  • Open in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor heater (sensor 1)

  • ECM

P0032

The air fuel Ratio (A/F) sensor heater current is higher than 10 A (1 trip detection logic).

  • Short in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor heater (sensor 1)

  • ECM

P101D

The 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 heater circuit

  • Air fuel ratio sensor heater (sensor 1)

  • ECM

WIRING DIAGRAM

Refer to DTC P2195 (Click here).

CAUTION / NOTICE / HINT

Note:

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

Tip:
  • 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.

  • 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).

      Tip:

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor (Click here).

    REPLACE AIR FUEL RATIO SENSOR

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE)

    1. U121740E02

      Disconnect the air fuel ratio sensor connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      C28-2 (+B) - Body ground

      Ignition switch ON

      11 to 14 V

      Table 1. Text in Illustration

      *a

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor)

    4. Reconnect the air fuel ratio sensor connector.

    CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - INTEGRATION RELAY)Click here

  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

      C28-1 (HA1A) - C111-27 (HA1A)

      Always

      Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection

      Condition

      Specified Condition

      C28-1 (HA1A) or C111-27 (HA1A) - Body ground

      Always

      10 kΩ or higher

    4. Reconnect the air fuel ratio sensor connector.

    5. Reconnect the ECM connector.

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

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

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs (Click here).

    5. Start the engine.

    6. Allow the engine to idle for 1 minute or more.

    7. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    8. Read the DTCs.

      Table 2. Result

      Result

      Proceed to

      DTC is not output

      A

      DTC P0031, P0032 or P101D is output

      B

    CHECK FOR INTERMITTENT PROBLEMS

    REPLACE ECM

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

    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the integration relay (EFI MAIN relay) from the engine room No. 1 relay block (Click here).

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

      Standard Resistance (Check for Open)

      Tester Connection

      Condition

      Specified Condition

      C28-2 (+B) - 1B-4

      Always

      Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection

      Condition

      Specified Condition

      C28-2 (+B) or 1B-4 - Body ground

      Always

      10 kΩ or higher

    4. Reconnect the air fuel ratio sensor connector.

    5. Reinstall the integration relay.

    GO TO ECM POWER SOURCE CIRCUIT

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