Click here

ECD SYSTEM (w/ DPF), Diagnostic DTC:P0031, P0032, P0051, P0052

Click here
Click here Click here
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)
A0157JHE08
Click here

DESCRIPTION

Tip:

  • For more information on the air fuel ratio sensor and Diesel Particulate Filter (DPF), refer to the following procedures (Click here).

  • These DTCs are related to the air fuel ratio sensor, although the titles say oxygen sensor.

The air fuel ratio sensor outputs a voltage* that is proportional to the air-fuel ratio. The air fuel ratio sensor output voltage is used to control the A/F mixture.

The air fuel ratio sensor is located after the Diesel Particulate Filter (DPF) catalytic converter. This sensor has been developed based on the structure and technology of the air fuel ratio sensor that is used for gasoline engines. The cover for the sensor electrode has been modified to suit its application in a diesel engine. This change allows the sensor to function effectively in this DPF type diesel engine, and it also avoids problems with sensor temperature and particulate matter (PM).

In order to reduce PM, the ECM adjusts the air-fuel ratio to a value slightly richer than that which would otherwise be used (note that this mixture is still leaner than the stoichiometric air fuel ratio). The ECM controls these adjustments on signals from the air fuel ratio sensor.

When the ECM performs PM forced regeneration (cleaning) by adding fuel using the exhaust fuel addition injector assembly, the air fuel ratio sensor feedback is used to ensure that an appropriate air fuel ratio is maintained.

*: This voltage change occurs only inside the ECM. It is not possible to measure this voltage at the sensor. The GTS can be used to monitor this voltage.

Tip:

The ECM provides a pulse width modulated control circuit to adjust current through the heater. The air fuel ratio sensor heater circuit uses a relay on the +B side of the circuit.

Table 1. P0031 (Bank 1), P0051 (Bank 2)
DTC Detection Drive Pattern DTC Detection Condition Trouble Area

  • Drive the vehicle at 50 km/h (30 mph) or more for a total of 300 seconds or more.

  • Check that "Exhaust Temperature B1S1" displays 200°C (392°F) or higher using the GTS.

Air fuel ratio sensor heater current is 0.8 A or less when the heater operates for 4 seconds.

(1 trip detection logic)

  • Open in air fuel ratio sensor heater circuit

  • air fuel ratio sensor heater

  • A/F relay

  • ECM
Table 2. P0032 (Bank 1), P0052 (Bank 2)
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Engine switch on (IG) for 5 seconds

Either condition is met (1 trip detection logic):


  • Air fuel ratio sensor heater current reaches the high limit (overcurrent is detected even though the air fuel ratio sensor heater is off)

  • Air fuel ratio sensor heater current is 0.8 A or more when the heater does not operate for 4 seconds.

  • Short in air fuel ratio sensor heater circuit

  • Air fuel ratio sensor heater

  • ECM
Table 3. Related Data List
DTC No. Data List

P0031

P0032

  • AFS Voltage B1S1

  • AF Lambda B1S1

  • Exhaust Temperature B1S1

P0052

P0053

  • AFS Voltage B2S1

  • AF Lambda B2S1

  • Exhaust Temperature B2S1
Click here

MONITOR DESCRIPTION

The inner surface of the air fuel ratio sensor element is exposed to outside air. The outer surface of the sensor element is exposed to exhaust gases. 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 of the exhaust and the outside air. The platinum coating amplifies the voltage generation. When heated, the sensor becomes very efficient. If the temperature of the exhaust is low, without supplemental heating, the sensor will not generate useful voltage signals. The ECM controls the heating by using a duty-cycle to regulate the average current in the heater element. If the heater current is out of the normal range, the output signals of the sensor are inaccurate and the ECM cannot regulate the air-fuel ratio properly. When the heater current is out of the normal operating range, the ECM interprets this as a malfunction and stores a DTC.

Click here

WIRING DIAGRAM

Click here

INSPECTION PROCEDURE

Note:

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

  • After replacing the ECM, the new ECM needs registration (Click here) and initialization (Click here).

  • After replacing the fuel supply pump assembly, the ECM needs initialization (Click here).

  • After replacing an injector assembly, the ECM needs registration (Click here).

Tip:

Read freeze frame data using the GTS. 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, and other data from the time the malfunction occurred.

Click here

PROCEDURE


  1. Click here

    INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. Inspect the air fuel ratio sensor (for bank 1 or bank 2) (Click here).


  2. Click here

    CHECK TERMINAL VOLTAGE (AIR FUEL RATIO SENSOR HEATER VOLTAGE)


    1. A015C1JE01

      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
      C159-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      C158-2 (+B) - Body ground Engine switch on (IG) 11 to 14 V
      Table 4. Text in Illustration
      *A for Bank 1
      *B for Bank 2
      *a

      Front view of wire harness connector

      (to Air Fuel Ratio Sensor)

  3. Click here

    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
      Table 5. for LHD
      Tester Connection Condition Specified Condition
      C159-1 (HAF1) - C45-45 (HA1A) Always Below 1 Ω
      C158-1 (HAF2) - C45-46 (HA2A) Always Below 1 Ω
      C159-1 (HAF1) or C45-45 (HA1A) - Body ground Always 10 kΩ or higher
      C158-1 (HAF2) or C45-46 (HA2A) - Body ground Always 10 kΩ or higher
      Table 6. for RHD
      Tester Connection Condition Specified Condition
      C159-1 (HAF1) - C46-45 (HA1A) Always Below 1 Ω
      C158-1 (HAF2) - C46-46 (HA2A) Always Below 1 Ω
      C159-1 (HAF1) or C46-45 (HA1A) - Body ground Always 10 kΩ or higher
      C158-1 (HAF2) or C46-46 (HA2A) - Body ground Always 10 kΩ or higher

  4. Click here

    REPLACE ECM


    1. Replace the ECM (Click here).


  5. Click here

    INSPECT A/F RELAY


    1. Inspect the A/F relay (Click here).


  6. Click here

    CHECK HARNESS AND CONNECTOR (A/F RELAY - A/F SENSOR)


    1. Disconnect the air fuel ratio sensor connector.

    2. Remove the A/F relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C159-2 (+B) - A/F relay terminal 3 Always Below 1 Ω
      C158-2 (+B) - A/F relay terminal 3 Always Below 1 Ω
      C159-2 (+B) or A/F relay terminal 3 - Body ground Always 10 kΩ or higher
      C158-2 (+B) or A/F relay terminal 3 - Body ground Always 10 kΩ or higher

  7. Click here

    INSPECT INTEGRATION RELAY (EFI MAIN 2)


    1. Inspect the integration relay (EFI MAIN 2) (Click here).


  8. Click here

    CHECK HARNESS AND CONNECTOR (A/F RELAY - INTEGRATION RELAY, BATTERY)


    1. Remove the A/F relay from the engine room relay block and junction block assembly.

    2. Remove the integration relay from the engine room relay block and junction block assembly.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A/F relay terminal 5 - Body ground Always 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A/F relay terminal 1 - 1A-4 Always Below 1 Ω
      A/F relay terminal 2 - Body ground Always Below 1 Ω
      A/F relay terminal 1 or 1A-4 - Body ground Always 10 kΩ or higher

  9. Click here

    CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM)


    1. Remove the integration relay from the engine room relay block and junction block assembly.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Table 7. for LHD
      Tester Connection Condition Specified Condition
      1A-2 - A38-44 (MREL) Always Below 1 Ω
      1A-2 or A38-44 (MREL) - Body ground Always 10 kΩ or higher
      Table 8. for RHD
      Tester Connection Condition Specified Condition
      1A-2 - A52-44 (MREL) Always Below 1 Ω
      1A-2 or A52-44 (MREL) - Body ground Always 10 kΩ or higher

  10. Click here

    REPLACE AIR FUEL RATIO SENSOR

    When DTC P0031 or P0032 is output:


    • Replace the air fuel ratio sensor (for bank 1) (Click here).

    When DTC P0051 or P0052 is output:


    • Replace the air fuel ratio sensor (for bank 2) (Click here).


  11. Click here

    REPLACE A/F RELAY


    1. Replace the A/F relay.


  12. Click here

    REPLACE INTEGRATION RELAY


    1. Replace the integration relay (EFI MAIN 2).


  13. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace harness or connector.


  14. Click here

    CHECK ECM POWER SOURCE CIRCUIT


    1. Check the ECM power source circuit (Click here).


  15. Click here

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

    2. Clear the DTCs (Click here).

    3. Turn the engine switch off for 30 seconds or more.

    4. Turn the engine switch on (IG).

    5. Turn the GTS on.

    6. Drive the vehicle at 50 km/h (30 mph) or more for a total of 300 seconds or more.

      Tip:

      "Exhaust Temperature B1S1" and "Exhaust Temperature B2S1" on the GTS screen should be 200°C (392°F) or higher.

    7. Confirm that the DTC is not output again.

      Tip:

      Perform the following procedure using the GTS to determine whether or not the DTC judgment has been carried out.


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

      2. Input DTC P0031, P0032, P0052 or P0053.

      3. Check that STATUS is NORMAL.

        Tip:

        • If STATUS is NORMAL, DTC judgment is complete and the system is determined to be normal.

        • If STATUS is INCOMPLETE or N/A, DTC judgment is incomplete. Drive the vehicle at 50 km/h (30 mph) or more for a total of 300 seconds or more again.


  16. Click here

    END