SFI SYSTEM, 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 is stored, the ECM enters fail-safe mode. The ECM turns off the air fuel ratio sensor heater in fail-safe mode. The ECM continues operating in fail-safe mode until the ignition switch is turned off.

  • Although the DTC titles say heated 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 (TWC) and located near the engine assembly.

  • The ECM provides 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.

    A00O6ZME09
DTC No. DTC Detection Condition Trouble Area

P0031

P0051

 The air fuel ratio sensor heater current is below 0.8 A (1 trip detection logic).

  • Open in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor heater (for bank 1, 2 sensor 1)

  • No. 1 integration relay (A/F)

  • ECM

P0032

P0052

 An air fuel ratio sensor heater current failure (1 trip detection logic).

  • Short in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor heater (for bank 1, 2 sensor 1)

  • No. 1 integration relay (A/F)

  • ECM

P101D

P103D

 The heater current is higher than a specified value while the heater is not operating (1 trip detection logic). ECM

Tech Tips


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

  • 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.

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 (TWC) 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 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.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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.


    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

  2. CHECK TERMINAL VOLTAGE (+B OF AIR FUEL RATIO SENSOR)

    A00O9LGE35
    Text in Illustration
    *A Bank 1
    *B Bank 2
    *a

    Front view of wire harness connector

    (to Air Fuel Ratio Sensor)

    1. Disconnect the air fuel ratio sensor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      C25-2 (+B) - Body ground Ignition switch ON 11 to 14 V
      C26-2 (+B) - Body ground Ignition switch ON 11 to 14 V

    3. Reconnect the air fuel ratio sensor connector.


    NG

    INSPECT NO. 1 INTEGRATION RELAY (A/F) 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
      C25-1 (HA1A) - C37-17 (HA1A) Always Below 1 Ω
      C26-1 (HA2A) - C37-19 (HA2A) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C25-1 (HA1A) or C37-17 (HA1A) - Body ground Always 10 kΩ or higher
      C26-1 (HA2A) or C37-19 (HA2A) - 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

    OK

  4. CHECK WHETHER DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester 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 / DTC.

    8. Read the DTCs.

      Result
      Result Proceed to
      No output A
      P0031, P0032, P0051, P0052, P101D or P103D B

    B

    REPLACE ECM Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  5. INSPECT NO. 1 INTEGRATION RELAY (A/F)


    1. Inspect the air fuel ratio sensor relay Click here.


    NG

    REPLACE NO. 1 INTEGRATION RELAY (A/F)

    OK

  6. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - NO. 1 INTEGRATION RELAY (A/F))


    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the No. 1 integration relay from the engine room relay block.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      C25-2 (+B) - 1B-8 Always Below 1 Ω
      C26-2 (+B) - 1B-8 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C25-2 (+B) or 1B-8 - Body ground Always 10 kΩ or higher
      C26-2 (+B) or 1B-8 - Body ground Always 10 kΩ or higher

    4. Reconnect the air fuel ratio sensor connector.

    5. Reinstall the No. 1 integration relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    CHECK ECM POWER SOURCE CIRCUIT Click here