Toyota Venza manuals

Toyota Venza: Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) (P0031,P0032,P101D)

Toyota Venza Service Manual / 1ar-fe Engine Control / Sfi System / Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) (P0031,P0032,P101D)

DESCRIPTION

Refer to DTC P2195 (See page ).


HINT:

  • 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 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.

DTC No.

DTC Detection Condition

Trouble Area

P0031

Air fuel ratio sensor heater current is less than 0.8 A, even when the air fuel ratio sensor heater duty cycle is 30% or higher (1 trip detection logic).

  • Open in air fuel ratio sensor heater circuit
  • Air fuel ratio sensor (bank 1 sensor 1)
  • EFI MAIN No. 2 relay
  • ECM

P0032

Air fuel ratio sensor heater current reaches the high limit (1 trip detection logic).

  • Short in air fuel ratio sensor heater circuit
  • Air fuel ratio sensor (bank 1 sensor 1)
  • EFI MAIN No. 2 relay
  • ECM

P101D

The heater current is higher than the specified value while the heater is not operating (1 trip detection logic).

ECM

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.

MONITOR STRATEGY

Related DTCs

P0031: Air Fuel Ratio Sensor Heater range check (Low Current)

P0032: Air Fuel Ratio Sensor Heater range check (High Current)

P101D: Air Fuel Ratio Sensor Heater Performance

Required Sensors/Components (Main)

Air fuel ratio sensor heater

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

10 seconds: P0031

10.24 seconds: P0032

1 second: P101D

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

P0031

Monitor runs whenever the following DTCs are not stored

None

All of the following conditions are met

-

Battery voltage

10.5 V or more

Time after heater on

5 seconds or more

Active heater off control

Not operating

Active heater on control

Not operating

Air fuel ratio sensor heater performance fail (P101D)

Not detected

Output duty cycle

30% or more

P0032

Monitor runs whenever the following DTCs are not stored

None

All of the following conditions are met

-

Battery voltage

10.5 V or more

Time after heater on

5 seconds or more

Output duty cycle

More than 0%

Active heater off control

Not operating

Active heater on control

Not operating

P101D

Monitor runs whenever the following DTCs are not stored

None

All of the following conditions are met

10 seconds or more

Battery voltage

10.5 V or more

Time after heater on

5 seconds or more

Output duty cycle

Less than 60%

Active heater off control

Not operating

Active heater on control

Not operating

Air fuel ratio sensor heater low current fail (P0031)

Not detected

TYPICAL MALFUNCTION THRESHOLDS

P0031

Heater on current

Less than 0.8 A

P0032

Both of the following conditions are met

-

Command to heater output

ON

Heater current detected by heater monitor IC

14 A or more

P101D

Both of the following conditions are met

-

Heater off current

More than 11 A

Heater current detected by heater monitor IC

14 A or more

COMPONENT OPERATING RANGE

P0031

Heater on current

0.8 A or more

P0032

Both of the following conditions are met

-

Command to heater output

ON

Heater current detected by heater monitor IC

Less than 14 A

P101D

Heater off current

11 A or less

CONFIRMATION DRIVING PATTERN


  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON and turn the Techstream on.
  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) (See page ).

  4. Turn the ignition switch off and wait for at least 30 seconds.
  5. Turn the ignition switch to ON and turn the Techstream 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 / Trouble Codes [E].
  10. Read the Pending DTCs.

    HINT:

    • 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 / Utility / All Readiness.
  12. Input the DTC: P0031, P0032, or P101D.
  13. Check the DTC judgment result.

    Techstream 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

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system has a malfunction.
  14. If the judgment result shows INCOMPLETE or N/A, perform steps [B] through [E] again.
  15. If no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

Refer to DTC P2195 (See page ).


CAUTION / NOTICE / HINT

NOTICE:

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

HINT:

  • Read freeze frame data using the Techstream. 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.
  • 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 function provided in the Active Test and monitor the air fuel ratio sensor output voltage (See page ). 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)

(a) Inspect the air fuel ratio sensor (See page ).


HINT:

Perform "Inspection After Repair" after replacing the air fuel ratio sensor (See page ).



NG

REPLACE AIR FUEL RATIO SENSOR


OK

2.

CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR)

(a) Disconnect the air fuel ratio sensor connector.


(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Switch Condition

Specified Condition

B7-2 (+B) - Body ground

Ignition switch ON

11 to 14 V

Text in Illustration

*a

Front view of wire harness connector

(to Air Fuel Ratio Sensor)


NG

GO TO STEP 5


OK

3.

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

(a) Disconnect the air fuel ratio sensor connector.

(b) Disconnect the ECM connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

B7-1 (HA1A) - B58-18 (HA1A)

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

B7-1 (HA1A) or B58-18 (HA1A) - Body ground

Always

10 kΩ or higher


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR


OK

4.

CHECK WHETHER DTC OUTPUT RECURS (DTC P0031, P0032 OR P101D)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Clear the DTCs (See page ).


(e) Turn the ignition switch off and wait for at least 30 seconds.

(f) Allow the vehicle to drive in accordance with the driving pattern described in the Confirmation Driving Pattern.

(g) Enter the following menus: Powertrain / Engine / Trouble Codes.

(h) Read the DTCs.

Result

Proceed to

DTC is not output

A

DTC P0031, P0032 or P101D is output

B


A

CHECK FOR INTERMITTENT PROBLEMS


B

REPLACE ECM

5.

INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (EFI MAIN NO. 2 RELAY)

(a) Inspect the EFI MAIN No. 2 relay (See page ).



NG

REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY


OK

6.

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - EFI MAIN NO. 2 RELAY)

(a) Disconnect the air fuel ratio sensor connector.

(b) Remove the engine room junction block assembly from the engine room relay block.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

B7-2 (+B) - 1F-9

Always

Below 1 Ω

Standard Resistance (Check for Short):

Tester Connection

Condition

Specified Condition

B7-2 (+B) or 1F-9 - Body ground

Always

10 kΩ or higher


OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - EFI MAIN NO. 2 RELAY)


NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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