СИСТЕМА SFI, 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 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 ignition 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.

    A01QOACE05
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) 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

 Comes on DTC stored
P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1) Air fuel ratio sensor heater current reaches the high limit (Hybrid IC high current limiter monitor input "Fail") (1 trip detection logic).

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

  • Air fuel ratio sensor (sensor 1)

  • ECM

 Comes on DTC stored
P101D A/F Sensor Heater Circuit Performance Bank 1 Sensor 1 Stuck ON 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 (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.

CONFIRMATION DRIVING PATTERN

A01QPDME58

  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON and turn the GTS on.

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

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

  5. Turn the ignition switch to ON and turn the GTS on [A].

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

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

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

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

  10. 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.

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

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

  13. 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

A01QS1GE01

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.

  • 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.

  • 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.

      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)


    1. A01QPY3C02
      *a

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor)

      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 Condition Specified Condition
      B7-2 (+B) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - EFI-MAIN NO.1 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
      Tester Connection Condition Specified Condition
      B7-1 (HA1A) - B93-27 (HA1A) Always Below 1 Ω
      B7-1 (HA1A) or B93-27 (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 ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs Click here.


      Powertrain > Engine and ECT > Clear DTCs

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

    6. Turn the ignition switch to ON.

    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.


      Powertrain > Engine and ECT > Trouble Codes

    10. Read the DTCs.

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

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

    B

    REPLACE ECM Click here