Inspection Procedure

HINT:

Malfunctioning areas can be identified by performing the A/F CONTROL^*1 (Control the Injection Volume for A/F sensor ^*2 ) 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 an intelligent tester or a Techstream.

^*1 : Intelligent tester

^*2 : Techstream

Connect the intelligent tester or the Techstream to the DLC3.
Start the engine.
Turn the tester ON.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Select the following menu items:
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
2. Techstream - Select: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
Monitor the output voltages of the A/F and HO2 sensors (AFSB1 S1 and O2S B1 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.

INJECTION VOLUME AND VOLTAGE SPECIFICATION

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1 S1 (A/F)	+25%	Rich	Less than 3.0 V
AFS B1 S1 (A/F)	-12.5%	Lean	More than 3.35 V
O2S B1 S2 (HO2)	+25%	Rich	More than 0.55 V
O2S B1 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.

A/F SENSOR AND HO2 SENSOR OUTPUT VOLTAGE SPECIFICATION

Case	A/F Sensor (Sensor 1) Output Voltage	HO2 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	A/F sensor A/F sensor heater A/F sensor circuit
3	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	HO2 sensor HO2 sensor heater HO2 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 A/F CONTROL or 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, select the following menu items:
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD 11 / ACTIVE TEST / A/F CONTROL / A/F CONTROL SYS / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2; then press the YES button and the ENTER button followed by the F4 button.
2. Techstream - Select: 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; then press the graph button on the Data List view.

HINT:

Read freeze frame data using an intelligent tester or a 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.
A low A/F sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high A/F 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 an intelligent tester or a Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the tester ON.
Select the following menu items:
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
2. Techstream - Select: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.

Result

RESULT REFERENCE

Result	Proceed to
P0171 or P0172	A
P0171 or P0172 and other DTCs	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
OK:

PCV hose is connected correctly and is not damaged.

NG : REPAIR OR REPLACE PCV HOSE

OK: Go to next step
CHECK AIR INDUCTION SYSTEM
1. Check the air induction system for vacuum leak (See ON-VEHICLE INSPECTION ).
  OK:
  
  No leak from air induction system.
NG : REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK: Go to next step

PERFORM ACTIVE TEST BY INTELLIGENT TESTER OR TECHSTREAM (A/F CONTROL)

Connect an intelligent tester or a Techstream to the DLC3.
Start the engine.
Turn the tester ON.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
Select the following menu items:
1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
2. Techstream - Select: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
Perform the A/F CONTROL (Control the Injection Volume for A/F Sensor) operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the voltage outputs of the Air Fuel Ratio (A/F) sensor and the Heated Oxygen (HO2) sensor (AFS B1S1 and O2S B1S2) 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.

Standard

INJECTION VOLUME AND VOLTAGE SPECIFICATION

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 (A/F)	+25%	Rich	Less than 3.0
AFS B1S1 (A/F)	-12.5%	Lean	More than 3.35
O2S B1S2 (HO2)	+25%	Rich	More than 0.55
O2S B1S2 (HO2)	-12.5%	Lean	Less than 0.4

Result:

RESULT REFERENCE

Status AFS B1S1	Status O2S B1S2	A/F Condition and A/F 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 Air induction system Fuel pressure Mass Air Flow (MAF) meter Engine Coolant Temperature (ECT) sensor	A
Rich	Rich	Actual air fuel ratio rich	-	Injector blockage or blockage Gas leak from exhaust system Ignition system Fuel pressure MAF meter ECT sensor	A
Lean	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B
Rich	Lean/Rich	A/F sensor malfunction	-	A/F sensor	B

Lean: During A/F CONTROL (Control the Injection Volume for A/F Sensor), the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V.

Rich: During A/F CONTROL (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 A/F CONTROL (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 INTELLIGENT TESTER OR TECHSTREAM (COOLANT TEMP)
1. Connect an intelligent tester or a Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester ON.
4. Select the following menu items:
  1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
  2. Techstream - Select: Powertrain / Engine and ECT / 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. Read the values using an intelligent tester or a Techstream (MAF).
  NOTE:
  - Turn the ignition switch to OFF.
  - Perform the inspection with the vehicle indoors and on a level surface.
  - Perform the inspection of the mass air flow meter while it is installed in the air cleaner case (installed on the vehicle).
  - During the test, do not use the exhaust air duct to perform suction on the exhaust pipe.
  1. Connect an intelligent tester or a Techstream to the DLC3.
  2. Turn the ignition switch to ON (do not start the engine).
  3. Turn the tester ON.
  4. Select the following menu items:
    1. Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DATA LIST / MAF.
    2. Techstream - Select: Powertrain / Engine and ECT / Data List / MAF.
  5. Wait for 30 seconds, and read the values on the tester.
    Standard value:
    
    Less than 0.48 g/sec
2. Inspect the mass air flow meter.
  1. Remove the mass air flow meter (See REMOVAL ).
  2. Using a work light, check that the platinum filament (heater portion) in the mass air flow meter has no foreign matter attached.
    OK:
    
    No foreign matter attached.
  3. Reinstall the mass air flow meter (See INSTALLATION ).
  Fig 1: Identifying Platinum Hot Wire In Mass Air Flow Meter
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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
OK:

No gas leak.

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 an intelligent tester or a Techstream. Select the following menu items:
  - Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / CYL #1 (to CYL #4).
  - Techstream - Select: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 Misfire Rate (to Cylinder #4 Misfire Rate)
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 an intelligent tester or a Techstream. Select the following menu items:
  - Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / CYL #1 (to CYL #4).
  - Techstream - Select: Powertrain / Engine and ECT / Data List / All Data / Cylinder #1 Misfire Rate (to Cylinder #4 Misfire Rate).
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 ).
NEXT
PERFORM CONFIRMATION DRIVING PATTERN

Fig 2: Vehicle Speed Graph
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect an intelligent tester or a Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester ON.
4. Clear DTCs (See DTC CHECK/CLEAR ).
5. Switch the ECM from normal mode to check mode using the tester (See CHECK MODE PROCEDURE ).
6. Start the engine and warm it up with all the accessories switched OFF.
7. Drive the vehicle at between 60 km/h and 120 km/h (38 mph and 75 mph) 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.
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P0171 OR P0172)

Connect an intelligent tester or a Techstream to the DLC3.
Turn the ignition switch to ON.
Turn the tester ON.
Select the following menu items:
1. Intelligent tester-Select: DIAGNOSIS/ ENHANCED OBD II / DTC INFO / CURRENT CODES.
2. Techstream - Select: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.

Result

RESULT REFERENCE

Result	Proceed to
No output	A
P0171 or P0172	B

B : REPLACE ECM (See REMOVAL )

A : END

INSPECT FUSE (EFI NO. 2 FUSE) (See INSPECTION PROCEDURE )
NG : CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE

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

OK : REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT (See ECM POWER SOURCE CIRCUIT )