Inspection Procedure

HINT:

Hand-held tester only:

It is possible the malfunctioning area can be found using the ACTIVE TEST A/F CONTROL operation. The A/F CONTROL operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.

Perform the ACTIVE TEST / A/F CONTROL operation.
HINT:

The A/F CONTROL operation lowers the injection volume 12.5% or increases the injection volume 25%.
1. Connect the hand-held tester to the DLC3 on the vehicle.
2. Turn the ignition switch ON.
3. Warm up the engine by running the engine at 2,500 RPM for approximately 90 seconds.
4. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5. Perform A/F CONTROL with the engine in an idle condition (press the right or left button).
  Result:
  
  A/F sensor reacts in accordance with increase and decrease of injection volume:
  
  +25 % --> Rich output: less than 3.0 V
  
  -12.5 % --> Lean output: more than 3.35 V
  
  Heated oxygen sensor reacts in accordance with increase and decrease of injection volume:
  
  +25 % --> Rich output: more than 0.55 V
  
  -12.5 % --> Lean output: less than 0.4 V

NOTE: The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay.

Fig 1: A/F Sensor Output Display Graph

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The following A/F CONTROL procedure enables a technician to check and graph the voltage outputs of both the A/F sensor and the heated oxygen sensor.

For displaying the graph, enter "ACTIVE TEST / A/F CONTROL / USER DATA", select "AFS B1S1 and O2S B1S2" by pressing "YES" and push "ENTER". Then, press "F4".

HINT:

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. 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.

Are there any other codes (besides DTC P0136) being output?
HINT:

If any other codes besides P0136 is output, perform the troubleshooting for those DTCs first.
1. YES : Go to relevant DTC chart (see DIAGNOSTIC TROUBLE CODE CHART ).
2. NO : Go to next step.
Check output voltage of heated oxygen sensor.
PREPARATION:
1. Connect the hand-held tester or OBD II scan tool to the DLC3.
2. After warm up the engine, race the engine at 2,500 RPM for 3 minutes.
CHECK:

Read the output voltage of the heated oxygen sensor when the engine is suddenly raced.

HINT:

Quickly accelerate the engine to 4,000 RPM 3 times by using the accelerator pedal.

OK:

Heated oxygen sensor output voltage: Alternates from 0.4 V or less to 0.5 V or more.
1. OK : Go to step 6 .
2. NG : Go to next step.
Check heated oxygen sensor (heater resistance) (see INSPECTION ).
1. NG : Replace heated oxygen sensor.
2. OK : Go to next step.

Check EFI main relay.

PREPARATION:

Remove the EFI main relay from the engine room J/B.

CHECK:

Inspect the EFI main relay.

OK:

TESTER CONNECTION SPECIFIED CONDITION

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

Fig 2: Identifying EFI Main Relay

NG : Replace EFI main relay.
OK : Go to next step.

Check for open and short in wire harness between ECM and heated oxygen sensor (see HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE in INTRODUCTION article).
Reference: Bank 1 Sensor 2 System Drawing

Fig 3: Heated Oxygen Sensor Wiring Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG : Repair or replace harness and connector.
2. OK : Replace heated oxygen sensor.
Perform confirmation driving pattern.
HINT:

Clear all DTCs prior to perform the confirmation driving pattern.
1. GO: Go to next step.
Is there DTC P0136 being output again?
1. NO : Check for intermittent problems.
2. YES : Replace heated oxygen sensor.