Toyota Tundra. Manual — part 1292

Fig. 365: Identifying Air Fuel Ratio Sensor Replacement Components With Torque Specification (2 Of 2)

ON-VEHICLE INSPECTION

1. INSPECT AIR FUEL RATIO SENSOR

a. Disconnect the 2 sensor connectors.

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

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

Standard resistance (for Bank 1 sensor 1)

TESTER CONNECTION SPECIFIED CONDITION

Standard resistance (for Bank 2 sensor 1)

TESTER CONNECTION SPECIFIED CONDITION

If the result is not as specified, replace the air fuel ratio sensor.

c. Connect the 2 sensor connectors.

Fig. 366: Identifying Air Fuel Ratio Sensor Connector Terminals

2. INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM

HINT:

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor
function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help
to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential
trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor
operation using the Techstream.

1. Connect the Techstream to the DLC3.

Tester Connection Condition Specified Condition

1 (HA1A) - 2 (+B) 20°C (68°F)

1.8 to 3.4 ohms

Tester Connection Condition Specified Condition

1 (HA2A) - 2 (+B) 20°C (68°F)

1.8 to 3.4 ohms

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra

2. Start the engine and turn the Techstream main switch ON.

3. Warm up the engine at an engine speed of 2500 RPM for approximately 90 seconds.

4. Enter the following menus: Engine and ECT/Active Test/Control the Injection Volume for A/F

sensor.

5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or

LEFT button to change the fuel injection volume).

6. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2

S1 and O2S B2 S2) displayed on the Techstream.

HINT:



The Control the Injection Volume for A/F sensor operation lowers the fuel injection volume
by 12.5% or increases the injection volume by 25%.



Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

VOLTAGE REFERENCE

VOLTAGE REFERENCE

Tester Display (Sensor)

Injection Volume Status

Voltage

AFS B1 S1 or AFS B2 S1 (A/F)

+25%

Rich

Less than 3.0 V

AFS B1 S1 or AFS B2 S1 (A/F)

-12.5%

Lean More than 3.35 V

O2S B1 S2 or O2S B2 S2 (HO2)

+25%

Rich More than 0.55 V

O2S B1 S2 or O2S B2 S2 (HO2)

-12.5%

Lean

Less than 0.4 V

NOTE:

The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds
and the Heated Oxygen (HO2) sensor has a maximum output delay of
approximately 20 seconds.

Case

A/F Sensor (Sensor 1)

Output Voltage

HO2 Sensor (Sensor 2)

Output Voltage

Main Suspected Trouble

Area

1

-

2



A/F sensor



A/F sensor heater



A/F sensor circuit

3



HO2 sensor



HO2 sensor heater



HO2 sensor circuit



Injector



Fuel pressure

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra



Following the Control the Injection Volume for A/F sensor procedure enables technicians to
check and graph the voltage outputs of both the A/F and HO2 sensors.



To display the graph, enter the following menus: Powertrain/Engine and ECT/Active
Test/Control the Injection Volume for A/F Sensor/A/F Control System/AFS B1 S1 and O2S
B1 S2 or AFS B2 S1 and O2S B2 S2.

REMOVAL

1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL

2. REMOVE FRONT NO. 3 EXHAUST PIPE SUB-ASSEMBLY (for Regular Cab Standard Deck)

a. Remove the 4 bolts and 2 nuts.

b. Disconnect the exhaust pipe from the exhaust pipe support, and remove the 2 gaskets.

3. REMOVE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (for Regular Cab Standard Deck)

a. Disconnect the air fuel ratio sensor connector.

b. Disconnect the heated oxygen sensor connector.

c. Remove the 3 nuts, exhaust pipe and gasket.

4. REMOVE FRONT NO. 2 EXHAUST PIPE ASSEMBLY (except Regular Cab Standard Deck)

a. Disconnect the air fuel ratio sensor connector.

b. Disconnect the heated oxygen sensor connector.

c. Remove the 3 nuts, 2 bolts, exhaust pipe and gasket.

5. REMOVE FRONT EXHAUST PIPE ASSEMBLY

a. Disconnect the air fuel ratio sensor connector.

b. Disconnect the heated oxygen sensor connector and 2 clamps.

c. Remove the 2 bolts.

d. Remove the 3 nuts, exhaust pipe and 2 gaskets.

6. REMOVE AIR FUEL RATIO SENSOR (for Bank 1 Sensor 1)

a. Using SST, remove the sensor.

4



Gas leakage from
exhaust system (Air-
fuel ratio extremely
rich or lean)

NOTE:



Some systems need to be initialized after the cable is reconnected
(see INITIALIZATION ).



After the ignition switch is turned OFF, the navigation system
requires approximately 90 seconds to record various types of
memory and settings. As a result, after turning the ignition switch
OFF, wait 90 seconds or more before disconnecting the cable from
the negative (-) battery terminal.

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (1GR-FE) - Tundra