Inspection Procedure

HINT:

Intelligent tester only: Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Heated Oxygen (HO2) sensors and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the A/F CONTROL operation using an intelligent tester.

Connect an intelligent tester 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: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A / F CONTROL.
Perform the A/F CONTROL 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 HO2 sensors (O2S B1S1 and OS2 B1S2) displayed on the tester.

HINT:

The A/F CONTROL 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

TESTER DISPLAY (SENSOR) INJECTION VOLUME

Tester Display (Sensor)	Injection Volumes	Status	Voltages
O2S B1S1 (Front HO2 Sensor)	+25 %	Rich	More than 0.5
O2S B1S1 (Front HO2 Sensor)	-12.5 %	Lean	Less than 0.4
O2S B1S2 (Rear HO2 Sensor)	+25 %	Rich	More than 0.5
O2S B1S2 (Rear HO2 Sensor)	-12.5 %	Lean	Less than 0.4

NOTE: The front HO2 sensor has an output delay of a few seconds and the rear HO2 sensor has a maximum output delay of approximately 20 seconds.

FRONT/REAR HO2 SENSOR (SENSOR 1) OUTPUT VOLTAGE

Case	Front HO2 Sensor (Sensor 1) Output Voltage		Rear HO2 Sensor (Sensor 2) Output Voltage		Main Suspected Trouble Area
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 0.5 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.5 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	Front HO2 sensor Front HO2 sensor heater Front Ho2 sensor circuit
Case 2	Output Voltage Almost no reaction	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Output Voltage More than 0.5 V Less than 0.4 V	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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 0.5 V Less than 0.4 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 A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the front and rear HO2 sensors.
To display the graph, select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST/ A/F CONTROL / USER DATA / AFS B1S2 and OS2 B1B2, and press the YES button and then the ENTER button followed by the F4 button.

NOTE: If the vehicle is short of fuel, the air-fuel ratio becomes lean and HO2 sensor DTCs are recorded, and the ECM illuminates the MIL.

HINT:

If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
Read freeze frame data using an intelligent tester or OBD II scan tool. 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 high HO2 sensor (sensor 1) voltage (0.5 V or more) could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
A low HO2 sensor (sensor 1) voltage (0.4 V or less) 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 P0134)

Connect an intelligent tester or OBD II scan tool to the DLC3.
Turn the ignition switch to ON.
Turn the tester or scan tool ON.
On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read DTCs.

If using an OBD II scan tool, refer to the instruction information.

Result

RESULT

Display (DTC Output)	Proceed to
P0134	A
P0134 and other DTCs	B

HINT:

If any DTCs other than P0134 are output, troubleshoot those DTCs first.

B : GO TO DTC CHART

A : Go to next step

READ VALUE OF INTELLIGENT TESTER OR OBD II SCAN TOOL (OUTPUT VOLTAGE OF HEATED OXYGEN SENSOR)
1. Connect the intelligent tester or OBD II scan tool to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester or scan tool ON.
4. Start the engine.
5. On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / O2S B1S1 and ENGINE SPD.
6. Warm up the engine until the engine coolant temperature reaches more than 75°C (169°F).
7. Rev the engine up to 4,000 rpm, 3 times using the accelerator pedal.
8. Read the output voltage of the front HO2 sensor displayed on the tester, when the engine speed is suddenly increased.
9. If using an OBD II scan tool, refer to the instruction information.
  Standard: HO2 sensor voltage output indicates 0.45 V or more (rich signal) at least once.
OK : Go to step 12

NG : GO TO NEXT STEP
CHECK PCV HOSE
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

INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

Disconnect the H5 HO2 sensor connector.

Measure the resistance between the terminals of the HO2 sensor connector.

Standard resistance

TESTER CONNECTIONS - SPECIFIED CONDITIONS (1 OF 3)

Tester Connections	Specified Conditions
HT (1) - +B (2)	Between 5 and 10 at 20°C (68°F)
HT (1) - E1 (4)	10 k or higher

Reconnect the HO2 sensor connector.

NG : REPLACE HEATED OXYGEN SENSOR

Fig 1: Inspecting Heated Oxygen Sensor (Heater Resistance)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : GO TO NEXT STEP

INSPECT EFI RELAY

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

Check the EFI relay resistance.

Standard resistance

TESTER CONNECTIONS - SPECIFIED CONDITIONS (2 OF 3)

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

Reinstall the EFI relay.

NG : REPLACE EFI RELAY

Fig 2: Inspecting EFI Relay

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : GO TO NEXT STEP

CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)

Disconnect the H5 HO2 sensor connector.

Fig 3: Checking Harness And Connector (Heated Oxygen Sensor - ECM)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn the ignition switch to ON.

Measure the voltage between the +B terminal of the H5 HO2 sensor connector and body ground.

Standard voltage

TESTER CONNECTIONS - SPECIFIED CONDITIONS (3 OF 3)

Tester Connections	Specified Conditions
+B (H5-2) - 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 - SPECIFIED CONDITIONS (CHECK FOR OPEN)

Tester Connections	Specified Conditions
HT (H5-1) - HT1A (E4-6)	Below 1
OX (H5-3) - OX1A (E4-22)	Below 1
E1 (H5-4) - Body ground	Below 1

Standard resistance (Check for short)

TESTER CONNECTIONS - SPECIFIED CONDITIONS (CHECK FOR SHORT)

Tester Connections	Specified Conditions
HT (H5-1) or HT1A (E4-6) - Body ground	10 k or higher
OX (H5-3) or OX1A (E4-22) - Body ground	10 k or higher

Reconnect the ECM connector.

NG : REPAIR OR REPLACE HARNESS OR CONNECTOR

OK : GO TO NEXT STEP

CHECK ENGINE CONTROL SYSTEM (MISFIRE OCCURS)
1. Check whether misfire occurs by monitoring DTC and/or Data List.
NG : GO TO TROUBLESHOOTING FOR MISFIRE

OK : GO TO NEXT STEP
CHECK AIR INDUCTION SYSTEM
1. Check the air induction system for vacuum leaks.
  OK : No leakage from air induction system.
NG : REPAIR OR REPLACE AIR INDUCTION SYSTEM

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 FUEL INJECTOR ASSEMBLY (INJECTION AND VOLUME)
1. Check the injector injection (whether fuel volume is high or low, and whether injection pattern is poor) (See INSPECTION ).
NG : REPLACE FUEL INJECTOR ASSEMBLY

OK : GO TO NEXT STEP
CHECK FOR EXHAUST GAS LEAKAGE
NG : REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT

OK : REPLACE HEATED OXYGEN SENSOR
PERFORM CONFIRMATION DRIVING PATTERN
NEXT

CHECK WHETHER DTC OUTPUT RECURS (DTC P0134)

Read DTCs using the intelligent tester or OBD II scan tool.
If using an intelligent tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

If using an OBD II scan tool, refer to the instruction information.

Result

RESULT

Display (DTC Output)	Proceed to
No output	A
P0134	B

B : REPLACE ECM

A : Go to next step

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

YES : DTC CAUSED BY RUNNING OUT OF FUEL