Inspection Procedure

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 and ECT / 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 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 B1 S1 (air fuel ratio)	+25%	' Rich	Less than 3.0 V
AFS B1 S1 (air fuel ratio)	-12.5%	Lean	More than 3.35 V
O2S B1 S2 (heated oxygen)	+25%	Rich	More than 0.55 V
O2S B1 S2 (heated oxygen)	-12.5%	Lean	Less than 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.

MAIN SUSPECTED TROUBLE AREA

Case	Air Fuel Ratio Sensor (Sensor 1) Output Voltage	Heated Oxygen Sensor (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 and ECT / Active Test / Control the Injection Volume for A/F Sensor / AFS B1 S1 and O2S B1 S2; then press the graph button on the Data List view.

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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
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 and ECT / 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 (See DIAGNOSTIC TROUBLE CODE CHART )

A: Go to Next Step

CHECK PCV HOSE CONNECTIONS
1. Inspect the PCV hose connections (See PCV VALVE ).
  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 leaks (See INTAKE SYSTEM ).
  OK: No leaks in intake system .
  
  NG: REPAIR OR REPLACE INTAKE SYSTEM
  
  OK: Go to Next Step

PERFORM ACTIVE TEST USING TECHSTREAM (A/F CONTROL)

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 and ECT / 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 B1S1 and O2S B1S2) 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 B1S1 (air fuel ratio)	+25%	Rich	Less than 3.0 V
AFS B1S1 (air fuel ratio)	-12.5%	Lean	More than 3.35 V
O2S B1S2 (heated oxygen)	+25%	Rich	More than 0.55 V
O2S B1S2 (heated oxygen)	-12.5%	Lean	Less than 0.4 V

Result

RESULT CHART

Status AFS B1S1	Status O2S B1S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Misfire	Suspected Trouble Area	Proceed to
Lean/Rich	Lean/Rich	Normal	-	-	C
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 blockage 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) is consistently more than 3.35 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.

Rich: During Control the Injection Volume for A/F Sensor, the AFS is consistently less than 3.0 V, and the O2S is consistently more 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

C: Go to step 15

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 and ECT / Data List / 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 MASS AIR FLOW METER ).
  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
INSPECT FOR EXHAUST GAS LEAK
1. Inspect 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 misfires may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / 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 misfires may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / 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 COMPONENT OPERATING RANGE )
NG: REPLACE AIR FUEL RATIO SENSOR (See REMOVAL )

OK: Go to Next Step
CHECK TERMINAL VOLTAGE (POWER SOURCE OF AIR FUEL RATIO SENSOR) (See COMPONENT OPERATING RANGE )
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 (AIR FUEL RATIO SENSOR ECM)

OK: Go to Next Step
REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor (See REMOVAL ).
PERFORM CONFIRMATION DRIVING PATTERN

Fig 1: Vehicle Speed Driving Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear DTCs (See DTC CHECK / CLEAR ).
5. Switch the ECM from normal mode to check mode using the Techstream (See CHECK MODE PROCEDURE ).
6. Start the engine and warm it up with all the accessories switched off.
7. Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) and at an engine speed of between 1400 rpm and 3200 rpm for 3 to 5 minutes.
HINT:

If the system is still malfunctioning, the MIL will be illuminated during step (g).

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)

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

Read the DTCs.

Result

RESULT CHART

Result	Proceed to
DTC is not output	A
DTC P0171 or P0172 is output	B

B: REPLACE ECM (See REMOVAL )

A: END

INSPECT FUSE (EFI NO. 2 FUSE)

Remove the EFI No. 2 fuse from the engine room relay block.

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

Standard Resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Condition	Specified Condition
EFI No. 2 fuse	Always	Below 1 Ω

Reinstall the EFI No. 2 fuse.
NG: REPLACE FUSE (EFI NO. 2 FUSE)

Fig 2: Identifying EFI No. 2 Fuse
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) AIR FUEL RATIO SENSOR)