SFI SYSTEM(w/ 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 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 power switch is turned off.

  • Although the DTC titles say 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.

    B002JBYE05
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) The heater current is less than the specified value while the heater is operating (1 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • EFI-MAIN NO. 2 relay

  • ECM

 Comes on DTC stored
P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1) The heater current is the specified value or higher while the heater is operating (1 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • EFI-MAIN NO. 2 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 (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
Output duty cycle 30% or higher
P0032
Output duty cycle Higher than 0%
P101D
Output duty cycle Less than 60%

CONFIRMATION DRIVING PATTERN

B002K7KE76

  1. Connect the GTS to the DLC3.

  2. Turn the power switch on (IG) and turn the GTS on.

  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

  4. Turn the power switch off and wait for at least 30 seconds.

  5. Turn the power switch on (IG) and turn the GTS on [A].

  6. Put the engine in inspection mode (maintenance mode).

    Click here

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

  8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 2500 rpm for 1 minute [C].

    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, perform steps [C] and [D] after charging control has completed.

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

  10. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].

  11. 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.

  12. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  13. Input the DTC: P0031, P0032 or P101D.

  14. 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].

    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.

  • 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)

    B002KDHC13
    *a

    Front view of wire harness connector

    (to Air Fuel Ratio Sensor)

    1. 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 Condition Specified Condition
      C5-2 (+B) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT 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
      Tester Connection Condition Specified Condition
      C5-1 (HA1A) - C48-23 (HA1A) Always Below 1 Ω
      C5-1 (HA1A) or C48-23 (HA1A) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.

      Click here


      Powertrain > Engine and ECT > Clear DTCs

    5. Turn the power switch off and wait for at least 30 seconds.

    6. Turn the power switch on (IG).

    7. Turn the GTS on.

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

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

    10. Read the DTCs.


      Powertrain > Engine and ECT > Trouble Codes
      Result
      Result Proceed to
      DTCs are not output A
      DTC P0031, P0032 or P101D is output B

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here

  5. INSPECT EFI-MAIN NO. 2 RELAY


    1. Inspect the EFI-MAIN No. 2 relay.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE EFI-MAIN NO. 2 RELAY

    OK

  6. CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 2 RELAY - AIR FUEL RATIO SENSOR, EFI-MAIN RELAY)


    1. Remove the EFI-MAIN NO. 2 relay from the No. 1 engine room relay block and junction block assembly.

    2. Remove the EFI-MAIN relay from the No. 1 engine room relay block and junction block assembly.

    3. Disconnect the air fuel ratio sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 (EFI-MAIN NO. 2 relay) - C5-2 (+B) Always Below 1 Ω
      1 (EFI-MAIN NO. 2 relay) - 3 (EFI-MAIN relay) Always Below 1 Ω
      2 (EFI-MAIN NO. 2 relay) - Body ground Always Below 1 Ω
      3 (EFI-MAIN NO. 2 relay) or C5-2 (+B) - Body ground Always 10 kΩ or higher
      1 (EFI-MAIN NO. 2 relay) or 3 (EFI-MAIN relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 2 RELAY)


    1. B002KUIC02
      *1 No. 1 Engine Room Relay Block and Junction Block Assembly
      *2 EFI-MAIN NO. 2 Relay

      Remove the EFI-MAIN NO. 2 relay from the No. 1 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
      5 (EFI-MAIN NO. 2 relay) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    GO TO ECM POWER SOURCE CIRCUIT Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - EFI-MAIN NO. 2 RELAY)