Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)


DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

CHECK TERMINAL VOLTAGE (AIR FUEL RATIO SENSOR HEATER VOLTAGE)

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

REPLACE ECM

INSPECT NO. 1 INTEGRATION RELAY (EFI MAIN2)

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

REPLACE AIR FUEL RATIO SENSOR

REPLACE NO. 1 INTEGRATION RELAY (EFI MAIN2)

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPAIR OR REPLACE HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - BATTERY)

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

DTC P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

DTC P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)


DESCRIPTION

HINT:
  1. For more information on the air fuel ratio sensor and Diesel Particulate Filter (DPF), refer to the following procedures (LandCruiser RM000000XSN04NX.html).
  2. This DTC is related to the air fuel ratio sensor, although the caption is the 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 engine. 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, 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.

Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.1Gd-Ftv Engine Control.Ecd System. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)


P0031
DTC Detection Drive Pattern
DTC Detection Condition
Trouble Area
  1. Drive the vehicle at 50 km/h (30 mph) or more for a total of 300 seconds or more.
  2. 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)
  1. Open in air fuel ratio sensor heater circuit
  2. air fuel ratio sensor heater
  3. A/F relay
  4. ECM

P0032
DTC Detection Drive Pattern
DTC Detection Condition
Trouble Area
Engine switch on (IG) for 5 seconds
Air fuel ratio sensor heater current is 0.8 A or more when the heater does not operate for 4 seconds.
(1 trip detection logic)
  1. Short in air fuel ratio sensor heater circuit
  2. Air fuel ratio sensor heater
  3. ECM

Related Data List
DTC No.
Data List
P0031
P0032
  1. AFS Voltage B1S1
  2. AF Lambda B1S1
  3. Exhaust Temperature B1S1

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.

WIRING DIAGRAM


Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.1Gd-Ftv Engine Control.Ecd System. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)


INSPECTION PROCEDURE

NOTICE:
  1. Inspect the fuses of circuits related to this system before performing the following inspection procedure.
  2. After replacing the ECM, the new ECM needs registration (LandCruiser RM0000012XK0AUX.html) and initialization (LandCruiser RM000000TIN08HX.html).
HINT:
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.
1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

  1. Inspect the air fuel ratio sensor (LandCruiser RM000004KG900NX.html).



NG
Go to step 7
OK


2.CHECK TERMINAL VOLTAGE (AIR FUEL RATIO SENSOR HEATER VOLTAGE)


    Land Cruiser, Land Cruiser Prado. Grj150 Trj150,155 Kdj150,155 Lj150, Gdj150,155.1Gd-Ftv Engine Control.Ecd System. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

  1. Disconnect the air fuel ratio sensor connector.

  1. Turn the engine switch on (IG).

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    C131-2 (+B) - Body ground
    		Engine switch on (IG)
    		11 to 14 V
    Text in Illustration
    *a
    		Front view of wire harness connector
    (to Air Fuel Ratio Sensor)

  1. Reconnect the air fuel ratio sensor connector.



NG
Go to step 5
OK


3.CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

  1. Disconnect the air fuel ratio sensor connector.

  1. Disconnect the ECM connector.

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

    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    C131-1 (HA1A) - G184-54 (HA1A)
    		Always
    		Below 1 Ω
    C131-1 (HA1A) or G184-54 (HA1A) - Body ground and other terminals
    		Always
    		10 kΩ or higher

  1. Reconnect the air fuel ratio sensor connector.

  1. Reconnect the ECM connector.



NG
Go to step 9
OK


4.REPLACE ECM

  1. Replace the ECM (LandCruiser RM0000013Z002DX.html).



NEXT
Go to step 11

5.INSPECT NO. 1 INTEGRATION RELAY (EFI MAIN2)

  1. Inspect the No. 1 integration relay (EFI MAIN2) (LandCruiser RM00000469101AX_01_0006.html).



NG
Go to step 8
OK


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

  1. Disconnect the air fuel ratio sensor connector.

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

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

    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    C131-2 (+B) - 1J-12
    		Always
    		Below 1 Ω
    C131-2 (+B) or 1J-12 - Body ground and other terminals
    		Always
    		10 kΩ or higher

  1. Reconnect the air fuel ratio sensor connector.

  1. Reinstall the No. 1 integration relay.



OK
Go to step 9

NG
Go to step 10

7.REPLACE AIR FUEL RATIO SENSOR

  1. Replace the air fuel ratio sensor (LandCruiser RM000004KGB00OX.html).



NEXT
Go to step 11

8.REPLACE NO. 1 INTEGRATION RELAY (EFI MAIN2)

  1. Replace the No. 1 integration relay (EFI MAIN2).



NEXT
Go to step 11

9.REPAIR OR REPLACE HARNESS OR CONNECTOR

  1. Repair or replace harness or connector.



NEXT
Go to step 11

10.REPAIR OR REPLACE HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - BATTERY)

  1. Repair or replace harness or connector (No. 1 integration relay - Battery).


NEXT


11.CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

  1. Connect the GTS to the DLC3.

  1. Clear the DTCs (LandCruiser RM000000PDK1E5X.html).

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

  1. Turn the engine switch on (IG) and turn the GTS on.

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

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

  1. Confirm that the DTC is not output again.

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

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

    2. Input DTC P0031 and/or P0032.

    3. Check that STATUS is NORMAL.

      HINT:
      1. If STATUS is NORMAL, DTC judgment is complete and the system is determined to be normal.
      2. 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.

NEXT

END