Inspection Procedure

HINT:

Techstream only:

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 Techstream.

Connect Techstream to the DLC3.
Start the engine and turn the tester on.
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
On the tester, select the following menu items: 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 in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).

Monitor the voltage output of the A/F and HO2 sensors (AFS B1S1 and OS2 B1S2) displayed on the tester.

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

INJECTION VOLUMES AND VOLTAGES STATUS

Tester Display (Sensor)	Injection Volumes	Status	Voltages
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

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.

INJECTION VOLUME

Case	A/F Sensor (Sensor 1) Output Voltage		HO2 Sensor (Sensor 2) Output Voltage		Main Suspected Trouble Areas
Case 1	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
Case 1	Output Voltage More than 3.35 V Less than 3.0 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.55 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	-
Case 2	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	A/F sensor A/F sensor heater A/F sensor circuit
Case 2	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.55 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	A/F sensor A/F sensor heater A/F sensor circuit
Case 3	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	HO2 sensor HO2 sensor heater HO2 sensor circuit
Case 3	Output Voltage More than 3.35 V Less than 3.0 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	HO2 sensor HO2 sensor heater HO2 sensor circuit
Case 4	Injection volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injection Volume +25% -12.5%	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely rich or lean)
Case 4	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

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, select the following menu items on the tester: 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.
Read freeze frame data using 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 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 Techstream to the DLC3.
Turn the ignition switch to the ON position and turn the tester on.
Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

Read DTCs.

Result

DTC RESULT DESCRIPTION CHART

Display (DTC Output)	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

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 leakage.
  OK: No leakage from air induction system.
NG: REPAIR OR REPLACE AIR INDUCTION SYSTEM

OK: Go to Next Step

PERFORM ACTIVE TEST BY TECHSTREAM (A/F CONTROL)

Connect Techstream to the DLC3.
Start the engine and turn the tester on.
Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
On the tester, select the following menu items: 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 in an idling condition.

Monitor the voltage outputs of the A/F and HOS sensors (AFS B1S1 and O2S B1S2) displayed on the tester.

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

STANDARD VOLTAGE

Tester Display (Sensor)	Injection Volumes	Status	Voltages
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

DTC RESULT DESCRIPTION CHART

Status AFS B1S1	Status O2S B1S2	A/F Condition and A/F Sensor Condition	Misfires	Suspected Trouble Areas	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 leakage 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 leakage or blockage Gas leakage 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 Control the Injection Volume for A/F Sensor, 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 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.

B: Go to step 11

C: Go to step 15

A: Go to Next Step

READ VALUE OF TECHSTREAM (COOLANT TEMP)
1. Connect Techstream to the DLC3.
2. Turn the ignition switch to the ON position and turn the tester on.
3. Select the following menu items: Powertrain / Engine and ECT / Data List / Coolant Temp.
4. Read the Coolant Temp twice, when the engine is cold and also when warmed up.
  Standard:
  
  With cold engine:
  
  Same as ambient air temperature
  
  With warm engine:
  
  Between 75°C and 95°C (167°F and 203°F)
NG: REPLACE ENGINE COOLANT TEMPERATURE SENSOR

OK: Go to Next Step
READ VALUE OF TECHSTREAM (MAF)
1. Connect Techstream to the DLC3.
2. Turn the ignition switch to the ON position and turn the tester on.
3. Select the following menu items: Powertrain / Engine and ECT / Data List / Coolant Temp.
4. Allow the engine to idle until the Coolant Temp reaches 75°C (167°F) or more.
5. Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
  Standard:
  
  MAF while engine idling:
  
  Between 1.4 g/sec. and 2.3 g/sec. (shift position: N, A/C: OFF).
  
  MAF at engine speed of 2,500 rpm:
  
  Between 5.4 g/sec. and 7.9 g/sec. (shift position: N, A/C: OFF).
NG: REPLACE MASS AIR FLOW METER

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 EXHAUST GAS LEAK
OK: No gas leakage.

NG: REPAIR OR REPLACE EXHAUST SYSTEM

OK: Go to Next Step
CHECK SPARKS AND IGNITION
1. Check for the sparks and the ignition (See INSPECTION ).
  HINT:
  
  If the spark plugs or ignition system malfunctions, engine misfire may occur. The misfire count can be read using Techstream. Select the following menu items: 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)
1. Inspect the fuel injector assembly (See INSPECTION ).
  HINT:
  
  If the injectors malfunction, engine misfire may occur. The misfire count can be read using Techstream. Select the following menu items: Powertrain / Engine and ECT / Data List / Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
NG: REPLACE FUEL INJECTOR ASSEMBLY

OK: Go to Next Step

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Disconnect the A24 A/F sensor connector.

Fig 1: Identifying A24 A/F Sensor Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance between the terminals of the A/F sensor connector.

Standard resistance

TESTER CONNECTIONS AND SPECIFIED CONDITIONS

Tester Connections	Specified Conditions
HT(1) - +B(2)	Between 1.8 Ω and 3.4 Ω at 20°C (68°F)
HT(1) - AF-(4)	10 kΩ or higher

Reconnect the A/F sensor connector.

NG: REPLACE AIR FUEL RATIO SENSOR

OK: Go to Next Step

INSPECT EFI RELAY

Remove the EFI relay from the engine room R/B.

Fig 2: Identifying EFI Relay

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the EFI relay resistance.

Standard resistance

TESTER CONNECTIONS AND SPECIFIED CONDITIONS

Tester Connections	Specified Conditions
3-5	10 kΩ or higher
3-5	Below 1 Ω (When battery voltage applied to terminals 1 and 2)

Reinstall the EFI relay.

NG: REPLACE EFI RELAY

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

Disconnect the A24 A/F sensor connector.

Fig 3: Identifying A24 A/F Sensor Connector And E4 ECM Connector

Turn the ignition switch to the ON position.

Measure the voltage between the +B terminal of the A/F sensor connector and body ground.

Standard voltage

TESTER CONNECTIONS AND SPECIFIED CONDITIONS

Tester Connections	Specified Conditions
+B (A24-2) - Body ground	Between 9 V and 14 V

Turn the ignition switch OFF.
Disconnect the E4 ECM connector.

Check the resistance.

Standard resistance (Check for open)

TESTER CONNECTIONS AND SPECIFIED CONDITIONS

Tester Connections	Specified Conditions
HT (A24-1) - HA1A (E4-5)	Below 1 Ω
AF+ (A24-3) - A1A+ (E4-23)	Below 1 Ω
AF- (A24-4) - A1 A- (E4-31)	Below 1 Ω

Standard resistance (Check for short)

TESTER CONNECTIONS AND SPECIFIED CONDITIONS

Tester Connections	Specified Conditions
HT (A24-1) or HA1A (E4-5) - Body ground	10 kΩ or higher
AF+ (A24-3) or A1A+ (E4-23) - Body ground	10 kΩ or higher
AF- (A24-4) or A1A- (E4-31) - Body ground	10 kΩ or higher

Reconnect the ECM connector.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

Fig 5: Identifying Driving Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect Techstream to the DLC3 (Procedure "A").
2. Turn the ignition switch to the ON position and turn the tester on (Procedure "B").
3. Clear DTCs (See DTC CHECK / CLEAR ) (Procedure "C").
4. Switch the ECM from normal mode to check mode using the tester (See CHECK MODE PROCEDURE ) (Procedure "D").
5. Start the engine and warm it up with all accessories switched OFF (Procedure "E").
6. Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) and at an engine speed of between 1,400 rpm and 3,200 rpm for 3 to 5 minutes (Procedure "F").
  HINT:
  
  If the system is still malfunctioning, the MIL will be illuminated during procedure "E".
  
  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)

On Techstream, select the following menu items: Powertrain / Engine and ECT / Trouble Codes.

Read DTCs.

Result

DTC RESULT DESCRIPTION CHART

Display (DTC Output)	Proceed to
No output	A
P0171 or P0172	B

B: Go to step 5

A : END