Toyota Tundra. Manual — part 1471

Fig. 377: Locating Knock Sensors With Nuts

AIR FUEL RATIO SENSOR

COMPONENTS

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Fig. 378: Identifying Air Fuel Ratio Sensor Replacement Components With Torque Specifications

ON-VEHICLE INSPECTION

1. INSPECT AIR FUEL RATIO SENSOR

a. Disconnect the 2 sensor connectors.

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

2008 Toyota Tundra

2008 ENGINE PERFORMANCE Engine Control System (2UZ-FE) - Tundra

Standard resistance (for Bank 1 sensor 1)

STANDARD RESISTANCE SPECIFICATION - (FOR BANK 1 SENSOR 1)

Standard resistance (for Bank 2 sensor 1)

STANDARD RESISTANCE SPECIFICATION - (FOR BANK 2 SENSOR 1)

If the result is not as specified, replace the sensor.

c. Connect the 2 sensor connectors.

Fig. 379: Identifying Air Fuel Ratio Sensor Connector Terminal

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 A/F CONTROL (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 A/F CONTROL (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 (2UZ-FE) - Tundra

2. Start the engine and turn the tester ON.

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

4. On the tester, enter the following menus: Powertrain/Engine/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 tester.

HINT:



The A/F CONTROL (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.

FUEL INJECTION - VOLTAGE SPECIFICATION

A/F SENSOR (SENSOR 1) OUTPUT 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 (2UZ-FE) - Tundra