Toyota Tundra Service Manual: Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) (P0031,P0032,P0051,P0052,P101D,P103D)

Toyota Tundra Service Manual / Engine, Hybrid System / 1ur-fe Engine Control / Sfi System / Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1) (P0031,P0032,P0051,P0052,P101D,P103D)

DESCRIPTION

Refer to DTC P2195 (See page ).

HINT:

  • Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
  • Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.
  • When one of these DTCs is stored, 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.
  • 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.

DTC No.

DTC Detection Condition

Trouble Area

P0031

P0051

Air-Fuel Ratio (A/F) sensor heater current is less than 0.8 A

(1 trip detection logic)

  • Open in A/F sensor heater circuit
  • A/F sensor heater (for Sensor 1)
  • Integration relay
  • ECM

P0032

P0052

Air-Fuel Ratio (A/F) sensor heater current failure

(1 trip detection logic)

  • Short in A/F sensor heater circuit
  • A/F sensor heater (for Sensor 1)
  • Integration relay
  • ECM

P101D

P103D

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

  • Open or short in A/F sensor heater circuit
  • 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 the 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 stores a DTC.

MONITOR STRATEGY

Related DTCs

P0031: A/F sensor heater (for Bank 1) open/short (Low electrical current)

P0032: A/F sensor heater (for Bank 1) open/short (High electrical current)

P0051: A/F sensor heater (for Bank 2) open/short (Low electrical current)

P0052: A/F sensor heater (for Bank 2) open/short (High electrical current)

P101D: A/F sensor heater (for Bank 1) performance

P103D: A/F sensor heater (for Bank 2) performance

Required Sensors/Components (Main)

A/F sensor heater

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

10 seconds: P0031 and P0051

10.24 seconds: P0032 and P0052

1 second: P101D and P103D

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

P0031 and P0051

Monitor runs whenever following DTCs not stored

P101D, P103D (Air fuel ratio sensor heater)

One of following conditions met

-

A. All of following conditions met

-

Battery voltage

10.5 V or higher

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 duty-cycle

10% or more

B. All of following conditions met

-

Output duty cycle

30% or more

P0032 and P0052

Monitor runs whenever following DTCs not stored

None

Battery voltage

10.5 V or higher

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 duty-cycle

More than 0%

P101D and P103D

Monitor runs whenever following DTCs not stored

P0031, P0051 (Air fuel ratio sensor heater)

Battery voltage

10.5 V or higher

Output duty cycle

below 60%

Active heater OFF control

Not operating

Active heater ON control

Not operating

TYPICAL MALFUNCTION THRESHOLDS

P0031 and P0051

Air fuel ratio sensor heater current

Below 0.8 A

P0032 and P0052

All of following condition met

-

Air fuel ratio sensor heater output

ON

Hybrid IC high current limiter monitor

Fail

P101D and P103D

All of following condition met

-

Air fuel ratio sensor heater OFF current

Higher than 11 A

Hybrid IC high current limiter monitor input

Fail

COMPONENT OPERATING RANGE

A/F sensor heater current

0.8 A or more

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON and turn the Techstream ON.
  3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  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 and ECT / 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 and ECT / Utility / All Readiness.
  12. Input the DTC: P0031, P0032, P0051, P0052, P101D or P103D.
  13. Check the DTC judgment result.

    Tester 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
  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

HINT:

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

    *: The No. 1 cylinder is the cylinder which is farthest from the transmission.

  • Bank 2 refers to the bank that does not include the No. 1 cylinder.
  • 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.
  • Read freeze frame data using the Techstream. 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.

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 (+B OF A/F SENSOR)

(a) Disconnect the A/F 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

D33-2 (+B) - Body ground

Ignition switch ON

11 to 14 V

D34-2 (+B) - Body ground

Ignition switch ON

11 to 14 V

Result

Result

Proceed to

NG

A

OK

B

B

GO TO STEP 5

A

3.

INSPECT INTEGRATION RELAY (A/F)

(a) Remove the integration relay from the engine room relay block.

(b) Inspect the A/F fuse.

(1) Remove the A/F fuse from the integration relay.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A/F fuse

Always

Below 1 Ω

(3) Reinstall the A/F fuse.

(c) Inspect the integration relay (A/F).

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2C-1 - 2A-4

No battery voltage applied to terminals 2A-2 and 2A-3

10 kΩ or higher

Battery voltage applied to terminals 2A-2 and 2A-3

Below 1 Ω

NG

REPLACE INTEGRATION RELAY (A/F)

OK

4.

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

(a) Disconnect the A/F sensor connector.

(b) Remove the integration relay from the engine room relay block.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D33-2 (+B) - 2A-4

Always

Below 1 Ω

D34-2 (+B) - 2A-4

Always

Below 1 Ω

2A-2 - 2B-5

Always

Below 1 Ω

2A-3 - Body ground

Always

Below 1 Ω

D33-2 (+B) or 2A-4 - Body ground

Always

10 kΩ or higher

D34-2 (+B) or 2A-4 - Body ground

Always

10 kΩ or higher

2A-2 or 2B-5 - Body ground

Always

10 kΩ or higher

OK

CHECK ECM POWER SOURCE CIRCUIT

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.

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

(a) Disconnect the A/F sensor connector.

(b) Disconnect the ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D33-1 (HA1A) - D74-22 (HA1A)

Always

Below 1 Ω

D34-1 (HA2A) - D74-20 (HA2A)

Always

Below 1 Ω

D33-1 (HA1A) or D74-22 (HA1A) - Body ground

Always

10 kΩ or higher

D34-1 (HA2A) or D74-20 (HA2A) - Body ground

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.

CHECK WHETHER DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Clear DTCs (See page ).

(e) Start the engine.

(f) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

(g) Read the output pending DTCs using the Techstream.

Result

Result

Proceed to

No pending DTC is output

A

Pending DTC P0031, P0032, P0051, P0052, P101D or P103D is output

B

A

CHECK FOR INTERMITTENT PROBLEMS

B

REPLACE ECM

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