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

The air fuel ratio sensor generates voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection time. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.

A three-way catalytic converter is used in order to convert the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) into less harmful substances. To allow the three-way catalytic converter to function effectively, it is necessary to keep the air fuel ratio of the engine near the stoichiometric air fuel ratio.

*: Value changes inside the ECM. Since the air fuel ratio sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

A01CECEE41
A01CCMGE10

Tech Tips


  • Although the DTC titles include 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 any of these DTCs are set, 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 engine switch is turned off.

  • 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.

    A01CCV8E02
DTC No. DTC Detection Condition Trouble Area

P0031

P0051

Air fuel ratio sensor heater (bank 1, 2 sensor 1) current less than 0.8 A

(1 trip detection logic)

  • Open in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit

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

  • A/F fuse

  • A/F relay

  • ECM

P0032

P0052

Air fuel ratio sensor heater (bank 1, 2 sensor 1) current fail

(1 trip detection logic)

  • Short in air fuel ratio sensor heater (bank 1, 2 sensor 1) circuit

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

  • A/F fuse

  • A/F relay

  • ECM

P101D

P103D

Air fuel ratio sensor 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


  • 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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

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

  • Bank 2 refers to the bank that does not include cylinder No. 1.

  • 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 (+B OF AIR FUEL RATIO SENSOR)


    1. A01CFINE01

      Disconnect the air fuel ratio sensor connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D27-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      D7-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V

    4. Reconnect the air fuel ratio sensor connector.


    NG

    CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - A/F 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 (Check for Open)
      Tester Connection Condition Specified Condition
      D27-1 (HA1A) - D1-86 (HA1A) Always Below 1 Ω
      D7-1 (HA2A) - D1-109 (HA2A) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D27-1 (HA1A) or D1-86 (HA1A) - Body ground Always 10 kΩ or higher
      D7-1 (HA2A) or D1-109 (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 (AIR FUEL RATIO SENSOR - ECM)

    OK

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032, P0051, P0052, P101D OR P103D)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

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

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

    7. Idle the engine for 5 minutes or more.

    8. Enter the following menus: Powertrain / Engine / DTC.

    9. Read the DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0031, P0032, P0051, P0052, P101D or P103D is output B

    B

    REPLACE ECM Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS Click here

  5. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - A/F RELAY)


    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the A/F 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
      D27-2 (+B) - A/F relay (3) Always Below 1 Ω
      D7-2 (+B) - A/F relay (3) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      D27-2 (+B) or A/F relay (3) - Body ground Always 10 kΩ or higher
      D7-2 (+B) or A/F relay (3) - Body ground Always 10 kΩ or higher

    4. Reinstall the A/F relay.

    5. Reconnect the air fuel ratio sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - A/F RELAY)

    OK

  6. INSPECT A/F RELAY


    1. Inspect the A/F relay Click here.


    NG

    REPLACE A/F RELAY

    OK

  7. CHECK HARNESS AND CONNECTOR (A/F RELAY - BODY GROUND)


    1. A01CCH2E01

      Remove the A/F relay from the engine room relay block.

    2. Measure the resistance according to the valve(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A/F relay (2) - Body ground Always Below 1 Ω

    3. Reinstall the A/F relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F RELAY - BODY GROUND)

    OK

  8. CHECK HARNESS AND CONNECTOR (A/F RELAY POWER SOURCE)


    1. A01CCH2E01

      Remove the A/F relay from the engine room relay block.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A/F relay (5) - Body ground Always 11 to 14 V

    3. Reinstall the A/F relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F RELAY - BATTERY)

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (A/F RELAY - EFI MAIN RELAY)