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

Двигатель. Toyota Rav4. Aca30, 33, 38 Ala30
Система Управления Двигателем 2Az-Fe. Toyota Rav4. Aca30, 33, 38 Ala30

DESCRIPTION

MONITOR DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR)

INSPECT INTEGRATION RELAY (EFI MAIN RELAY)

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

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

CHECK WHETHER DTC OUTPUT RECURS

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

Refer to DTC P2195 (see page RAV4_ACA30 RM000000WC4017X_01.html).
УКАЗАНИЕ:
  1. Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
  2. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.
  3. When either of these DTCs is set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.

  4. The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The A/F sensor heater circuit uses a relay on the +B side of the circuit.


    Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)


DTC No.
DTC Detection Condition
Trouble Area
P0031
Air-Fuel Ratio (A/F) sensor heater current less than 0.8 A
(1 trip detection logic)
  1. Open in A/F sensor heater circuit
  2. A/F sensor heater (sensor 1)
  3. Integration relay (EFI MAIN relay)
  4. ECM
P0032
Air-Fuel Ratio (A/F) sensor heater current more than 10 A
(1 trip detection logic)
  1. Short in A/F sensor heater circuit
  2. A/F sensor heater (sensor 1)
  3. Integration relay (EFI MAIN relay)
  4. ECM

MONITOR DESCRIPTION

The ECM uses information from the Air-Fuel Ratio (A/F) 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 (TWC) to purify the exhaust gases.
The A/F 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 A/F 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 A/F sensor becomes inaccurate, as a result, the ECM is unable to regulate air-fuel ratio properly.
When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and sets a DTC.
Example:
The ECM sets DTC P0032 when the current in the A/F sensor heater is more than 10 A. Conversely, when the heater current is less than 0.8 A, DTC P0031 is set.

WIRING DIAGRAM

Refer to DTC P2195 (see page RAV4_ACA30 RM000000WC4017X_07.html).

INSPECTION PROCEDURE

УКАЗАНИЕ:
Read freeze frame data using the intelligent tester. 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, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

  1. Disconnect the B7 A/F sensor connector.

  1. Measure the resistance of the A/F sensor connector.

    Standard resistance:
    Tester Connection
    		Specified Condition
    HA1A (1) - +B (2)
    		1.8 Ω to 3.4 Ω at 20°C (68°F)
    HA1A (1) - A1A- (4)
    		10 kΩ or higher

  1. Reconnect the A/F sensor connector.



NG
REPLACE AIR FUEL RATIO SENSOR
OK


2.CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR)
Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

  1. Disconnect the B7 A/F sensor connector.

  1. Turn the ignition switch on (IG).

  1. Measure the voltage between the terminals of the B7 A/F sensor connector and body ground.

    Standard voltage:
    Tester Connection
    		Specified Condition
    +B (B7-2) - Body ground
    		9 to 14 V

  1. Reconnect the A/F sensor connector.



OK
Перейдите к шагу 5
NG


3.INSPECT INTEGRATION RELAY (EFI MAIN RELAY)

  1. Remove the integration relay from the engine room relay block.



  1. Inspect the EFI MAIN fuse.



      Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

    1. Remove the EFI MAIN fuse from the integration relay.

    2. Measure the EFI MAIN fuse resistance.

      Standard resistance:
      Below 1 Ω

    3. Reinstall the EFI MAIN fuse.

  1. Inspect the EFI MAIN relay.

    1. Measure the EFI MAIN relay resistance.

      Standard resistance:
      Tester Connection
      		Specified Condition
      1C-1 - 1A-4
      		10 kΩ or higher
      Below 1 Ω
      (Apply battery voltage between terminals 1A-2 and 1A-3)

  1. Reinstall the integration relay.



NG
REPLACE INTEGRATION RELAY
OK


4.CHECK HARNESS AND CONNECTOR (A/F SENSOR - INTEGRATION RELAY)
Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

  1. Disconnect the B7 A/F sensor connector.

  1. Remove the integration relay from the engine room No. 1 relay block (R/B).

  1. Measure the resistance.

    Standard resistance (Check for open):
    Tester Connection
    		Specified Condition
    +B (B7-2) - Engine room No. 1 R/B (1A-4)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connection
    		Specified Condition
    +B (B7-2) or Engine room
    Engine room No. 1 R/B (1A-4) - Body ground
    		10 kΩ or higher

  1. Reconnect the A/F sensor connector.

  1. Reinstall the integration relay.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

CHECK ECM POWER SOURCE CIRCUIT

5.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
Toyota Rav4. Aca30, 33, 38 Ala30.Система Управления Двигателем 2Az-Fe.Система Sfi. Dtc P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

  1. Disconnect the B7 A/F sensor connector.

  1. Disconnect the B32 ECM connector.

  1. Measure the resistance.

    Standard resistance (Check for open):
    Tester Connection
    		Specified Condition
    HA1A (B7-1) - HA1A (B32-109)
    		Below 1 Ω
    Standard resistance (Check for short):
    Tester Connection
    		Specified Condition
    HA1A (B7-1) or HA1A (B32-109) - Body ground
    		10 kΩ or higher

  1. Reconnect the A/F sensor connector.

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


6.CHECK WHETHER DTC OUTPUT RECURS

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch on (IG).

  1. Turn the tester ON.

  1. Clear DTCs (see page RAV4_ACA30 RM000000PDK013X.html).

  1. Start the engine.

  1. Allow the engine to idle for 1 minute or more.

  1. Select the following menu items: Powertrain / Engine and ECT / DTC.

  1. Read DTCs.


Result:

Display (DTC Output)
Proceed to
No output
A
P0031 or P0032
B


B
REPLACE ECM
A

CHECK FOR INTERMITTENT PROBLEMS