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.
Put the engine in inspection mode (See CHECK MODE PROCEDURE ).
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 Techstream, 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 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 (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) 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 in the fuel injection volume.

Standard

FUEL INJECTION VOLUME REFERENCE

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 or AFS B2S1 (A/F)	+25%	Rich	Less than 3.0
AFS B1S1 or AFS B2S1 (A/F)	-12.5%	Lean	More than 3.35
O2S B1S2 or O2S B2S2 (HO2)	+25%	Rich	More than 0.55
O2S B1S2 or O2S B2S2 (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.

A/F SENSOR OUTPUT VOLTAGE REFERENCE

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	Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich)

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, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 or AFS B2 S1 and O2S B1 S2 or O2S B2 S2 then press the graph button on the Data List view.

HINT:

DTC P2A00 or P2A03 may also be set, when the air-fuel ratio is stuck rich or lean.
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.
Read freeze frame data using Techstream. The ECM (Included in HV control ECU) 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 running or stopped, 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.

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00 AND/OR P2A03)

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

Read the DTCs.

Result

RESULT CHART

Display (DTC Output)	Proceed to
P2A00 and/or P2A03	A
P2A00 and/or P2A03 and other DTCs	B

HINT:

If any DTCs other than P2A00 or P2A03 are output, troubleshoot those DTCs first.

B: GO TO DTC CHART

A: Go to next step

READ VALUE USING TECHSTREAM (OUTPUT VOLTAGE OF A/F SENSOR)

Connect Techstream to the DLC3.
Put the engine in inspection mode (See CHECK MODE PROCEDURE ).
Start the engine.
Turn the tester ON.
Warm up the Air-Fuel Ratio (A/F) sensor at an engine speed of 2,500 rpm for 90 seconds.
On the tester, enter the following menus: Powertrain / Engine and ECT / Data List / AFS B1 S1 or AFS B2 S7 and Engine Speed.

Check the the A/F sensor voltage three times, when the engine is in each of the following conditions:

While idling (check for at least 30 seconds)
At an engine speed of approximately 2,500 rpm (without any sudden changes in engine speed)

Raise the engine speed to 4,000 rpm and then quickly release the accelerator pedal so that the throttle valve is fully closed.

Standard voltage

TERMINALS VOLTAGE REFERENCE

Condition	A/F Sensor Voltage Variation	Reference
(1) and (2)	Changes at approximately 3.3 V	Between 3.1 V and 3.5 V
(3)	Increases to 3.8 V or more	This occurs during engine deceleration when fuel-cut performed

HINT:

For more information, see the diagrams below.

Fig 1: A/F Sensor Normal And Malfunction Condition Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

If the output voltage of the A/F sensor remains at approximately 3.3 V (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have an open circuit, (this will also happen if the A/F sensor heater has an open circuit.)
If the output voltage of the A/F sensor remains at either approximately 3.8 V or more, or 2.8 V or less (see Malfunction Condition diagram) under any conditions, including those above, the A/F sensor may have a short circuit.
The ECM (Included in HV control ECU) stops fuel injection (fuel cut) during engine deceleration. This causes a lean condition and results in a momentary increase in the A/F sensor output voltage.
The ECM must establish a closed throttle valve position learning value to perform fuel cut. If the battery terminal has been reconnected, the vehicle must be driven over 10 mph (16 km/h) to allow the ECM to learn the closed throttle valve position.
When the vehicle is driven: The output voltage of the A/F sensor may be below 2.8 V during fuel enrichment. The vehicle translates this as a sudden increase in speed with the accelerator pedal fully depressed when trying to overtake another vehicle. The A/F sensor is functioning normally.
The A/F sensor is a current output element; therefore, the current is converted into a voltage inside the ECM. Measuring the voltage at the connectors of the A/F sensor or ECM will show a constant voltage result.

NG: Go to step 9

OK: Go to next step

PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using Techstream.

Enter the following menus: Powertrain / Engine and ECT / Trouble Code.

Result

RESULT CHART

Display (DTC Output)	Proceed to
P2A00 and/or P2A03	A
No output	B

B: Go to step 8

A: Go to next step

REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using Techstream.

Enter the following menus: Powertrain / Engine and ECT / Trouble Code.

Result

RESULT CHART

Display (DTC Output)	Proceed to
No output	A
P2A00 and/or P2A03	B

B: REPLACE HV CONTROL ECU AND PERFORM CONFIRMATION DRIVING PATTERN

A: Go to next step

CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS

YES: DTC CAUSED BY RUNNING OUT OF FUEL

INSPECT AIR FUEL RATIO SENSOR

Disconnect the A3 or A4 A/F sensor connector.

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

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HA1A, HA2A (1) - +B (2)	1.8 to 3.4 Ω at 200°C (68°F)
HA1A, HA2A (1) - A1A-, A2A- (4)	10 kΩ or higher

Reconnect the A/F sensor connector.

Fig 2: Identifying Terminals Of A3 Or A4 A/F Sensor Connectors
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPLACE AIR FUEL RATIO SENSOR

OK: Go to next step

INSPECT A/F RELAY

Remove the A/F relay from the engine room R/B.

Measure A/F relay resistance.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1 Ω (when battery voltage applied to terminals 1 and 2)

NG: REPLACE A/F RELAY

OK: Go to next step

CHECK HARNESS AND CONNECTOR (A/F SENSOR - HV CONTROL ECU)

Disconnect the A3 and A4 A/F sensor connectors.
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 CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
+B (2) - Body ground	9 to 14 V

Turn the ignition switch off.
Disconnect the H33 HV control ECU connector.

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

Standard resistance (Check for open)

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HA1A (A4-1) - HA1A (H33-4)	Below 1 Ω
A1A+ (A4-3) - A1A+ (H33-22)	Below 1 Ω
A1A- (A4-4) - A1A- (H33-30)	Below 1 Ω
HA2A (A3-1) - HA2A (H33-3)	Below 1 Ω
A2A+ (A3-3) - A2A+ (H33-23)	Below 1 Ω
A2A- (A3-4) - A2A- (H33-31)	Below 1 Ω

Fig 4: Identifying Terminals Of H33 HV Control ECU Connector

Standard resistance (Check for short)

TESTER CONNECTION SPECIFIED CONDITION CHART

Tester Connection	Specified Condition
HA1A (A4-1) or HA1A (H33-4) - Body ground	10 kΩ or higher
A1A+ (A4-3) or A1A+ (H33-22) - Body ground	10 kΩ or higher
A1A- (A4-4) or A1A- (H33-30) - Body ground	10 kΩ or higher
HA2A (A3-1) or HA2A (H33-3) - Body ground	10 kΩ or higher
A2A+ (A3-3) or A2A+ (H33-23) - Body ground	10 kΩ or higher
A2A- (A3-4) or A2A- (H33-31) - Body ground	10 kΩ or higher

Reconnect the HV control ECU connector.
Reconnect the A/F sensor connector.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

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
CHECK PCV HOSE
OK: PCV hose is connected correctly and is not damaged.

NG: REPAIR OR REPLACE PCV HOSE

OK: Go to next step
CHECK FUEL PRESSURE
1. Check the fuel pressure (See ON-VEHICLE INSPECTION ).
  Standard:
  
  304 to 343 kPa (3.1 to 3.5 kgf/cm ² , 44.1 to 49.7 psi)
NG: REPAIR OR REPLACE FUEL SYSTEM

OK: Go to next step
INSPECT FUEL INJECTOR
1. Check the injector injection (See INSPECTION ).
  Standard:
  
  13 cm ³ (0.8 cu in.) or less
NG: REPLACE FUEL INJECTOR ASSEMBLY

OK: Go to next step
REPLACE AIR FUEL RATIO SENSOR
PERFORM CONFIRMATION DRIVING PATTERN

CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00 AND/OR P2A03)

Read the DTCs using Techstream.

Enter the following menus: Powertrain / Engine and ECT /Trouble Code.

Result

RESULT CHART

Display (DTC Output)	Proceed to
No output	A
P2A00 and/or P2A03	B

B: REPLACE HV CONTROL ECU

A: Go to next step

CONFIRM WHETHER VEHICLE HAS RUN OUT OF FUEL IN PAST
NO: CHECK FOR INTERMITTENT PROBLEMS

YES: DTC CAUSED BY RUNNING OUT OF FUEL