Inspection Procedure

WARNING: This page is about a different variant/trim than selected.

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 sensor, heated oxygen 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.

Connect the Techstream to the DLC3.
Start the engine.
Turn the Techstream on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain/Engine/Active Test/Control the Injection Volume for A/F Sensor.
Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1 S1 and O2S B1 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 STATUS CHART

Techstream Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1 S1 (Air fuel ratio)	+25%	Rich	Below 3.1 V
AFS Voltage B1 S1 (Air fuel ratio)	-12.5%	Lean	Higher than 3.4 V
O2S B1 S2 (Heated oxygen)	+25%	Rich	Higher than 0.55 V
O2S B1 S2 (Heated oxygen)	-12.5%	Lean	Below 0.4 V

NOTE: The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

AIR FUEL RATIO SENSOR REFERENCE

Case	Air Fuel Ratio Sensor (Bank 1 Sensor 1) Output Voltage	Heated Oxygen Sensor (Bank 1 Sensor 2) Output Voltage	Main Suspected Trouble Area
1	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
2	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injector Fuel pressure Gas leak from exhaust system (Air fuel ratio extremely rich or lean)

Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain/Engine/Active Test/Control the Injection Volume for A/F Sensor/All Data/AFS Voltage B1 S1 and O2S B1 S2; then press the graph button on the Data List view.
NOTE: 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.
A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171 OR P0172)

Connect the Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the Techstream on.
Enter the following menus: Powertrain/Engine/Trouble Codes.

Read the DTCs.

Result

RESULT CHART

Result	Proceed to
DTC P0171 or P0172 is output	A
DTC P0171 or P0172 and other DTCs are output	B

HINT:

If any DTCs other than P0171 or P0172 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART

A: Go to next step

CHECK PCV HOSE CONNECTIONS
1. Check the PCV hose connections.
  OK:
  
  PCV hose is connected correctly and is not damaged.
  
  NG: REPAIR OR REPLACE PCV HOSE
  
  OK: Go to next step
CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leakage (See ON-VEHICLE INSPECTION ).
  OK:
  
  No leakage from intake system.
  
  NG: REPAIR OR REPLACE INTAKE SYSTEM
  
  OK: Go to next step

PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME)

Connect the Techstream to the DLC3.
Start the engine.
Turn the Techstream on.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain/Engine/Active Test/Control the Injection Volume for A/F Sensor.
Perform the Control the Injection Volume for A/F Sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (AFS Voltage B1 S1 and O2S B1 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.

Standard

VOLTAGE STATUS CHART

Techstream Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1 S1 (Air fuel ratio)	+25%	Rich	Below 3.1 V
AFS Voltage B1 S1 (Air fuel ratio)	-12.5%	Lean	Higher than 3.4 V
O2S B1 S2 (Heated oxygen)	+25%	Rich	Higher than 0.55 V
O2S B1 S2 (Heated oxygen)	-12.5%	Lean	Below 0.4 V

Result

RESULT CHART

Status AFS Voltage B1 S1	Status O2S B1 S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Misfire	Suspected Trouble Area	Proceed to
Lean	Lean	Actual air fuel ratio lean	May occur	PCV valve and hose PCV hose connections Injector blockage Gas leak from exhaust system Intake system Fuel pressure Mass air flow meter Engine coolant temperature sensor	A
Rich	Rich	Actual air fuel ratio rich	-	Injector leak or blockage Gas leak from exhaust system Ignition system Fuel pressure Mass air flow meter Engine coolant temperature sensor	A
Lean	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
Rich	Lean/Rich	Air fuel ratio sensor malfunction	-	Air fuel ratio sensor	B
Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (AFS Voltage B1 S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1 S2) is consistently below 0.4 V. Rich: During Control the Injection Volume for A/F Sensor, the AFS Voltage B1 S1 is consistently below 3.1 V, and the O2S B1 S2 is consistently higher than 0.55 V. Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the heated oxygen sensor alternates correctly.

B: Go to step 11

A: Go to next step

READ VALUE USING TECHSTREAM (COOLANT TEMP)
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain/Engine/Data List/All Data/Coolant Temp.
5. Read the Data List twice, when the engine is both cold and warmed up.
  Standard value:
  
  With cold engine: Same as ambient air temperature.
  
  With warm engine: 80 to 100°C (176 to 212°F).
  
  NG: REPLACE ENGINE COOLANT TEMPERATURE SENSOR (See REMOVAL )
  
  OK: Go to next step
INSPECT MASS AIR FLOW METER
1. Inspect the mass air flow meter (See INSPECTION PROCEDURE ).
  NG: REPLACE MASS AIR FLOW METER (See REMOVAL )
  
  OK: Go to next step
CHECK FUEL PRESSURE
1. Check the fuel pressure (See ON-VEHICLE INSPECTION ).
  NG: REPAIR OR REPLACE FUEL SYSTEM
  
  OK: Go to next step
CHECK FOR EXHAUST GAS LEAK
1. Check for exhaust gas leaks.
  OK:
  
  No gas leaks.
  
  NG: REPAIR OR REPLACE EXHAUST SYSTEM
  
  OK: Go to next step
CHECK SPARK AND IGNITION
HINT:
- Refer to the ignition system inspection procedure (See ON-VEHICLE INSPECTION ).
- If the spark plugs or ignition system malfunctions, engine misfire may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain/Engine/Data List/All Data/Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
  NG: REPAIR OR REPLACE IGNITION SYSTEM
  
  OK: Go to next step
INSPECT FUEL INJECTOR ASSEMBLY (INJECTION AND VOLUME)
HINT:
- Refer to the fuel injector inspection procedure (See INSPECTION ).
- If the injectors malfunction, engine misfire may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain/Engine/Data List/All Data/Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
  NG: REPLACE FUEL INJECTOR ASSEMBLY (See REMOVAL )
  
  OK: Go to next step
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) (See INSPECTION PROCEDURE )
NG: REPLACE AIR FUEL RATIO SENSOR (See REMOVAL )

OK: Go to next step
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR) (See INSPECTION PROCEDURE )
NG: Go to step 17

OK: Go to next step
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM) (See INSPECTION PROCEDURE )
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to next step
REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor (See REMOVAL ).
PERFORM CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
  
  Fig 1: Vehicle Speed Driving Pattern
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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).
4. Turn the ignition switch off.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Start the engine and warm it up (until the engine coolant temperature is 75°C (167°F) or higher) with all the accessories switched off [B].
7. With the engine warmed up, idle the engine for 2 minutes or more [C].
8. Drive the vehicle at between 37 and 75 mph (60 and 120 km/h) and at an engine speed of between 1400 and 3200 rpm for 5 minutes or more [D].
  NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected.

CHECK WHETHER DTC OUTPUT RECURS (DTC P0171 OR P0172)

Enter the following menus: Powertrain/Engine/Utility/All Readiness.
Input the DTC: P0171 or P0172.

Check the DTC judgment.

Result

RESULT CHART

Result	Proceed to
NORMAL (DTC is not output)	A
ABNORMAL (DTC P0171 or P0172 is output)	B

B: REPLACE ECM (See REMOVAL )

A: REPAIR COMPLETED

INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY (EFI MAIN O. 2 RELAY)
1. Inspect the engine room junction block assembly (See INSPECTION ).
  NG: REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY (See REMOVAL )
  
  OK: Go to next step
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - EFI MAIN NO. 2 RELAY) (See INSPECTION PROCEDURE )
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

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