Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.

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.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430)
1. Connect the hand-held tester or the OBD II scan tool to the DLC3.
2. Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.
3. Select the item: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
4. Read DTCs.
  Result:
  
  Fig 1: DTC Output Result Table
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HINT: If any other codes besides P0420 and/or P0430 are output, perform troubleshooting for those DTCs first.

B: GO TO RELEVANT DTC CHART (See DIAGNOSTIC TROUBLE CODE CHART )

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

OK: GO TO NEXT STEP.
INSPECT AIR FUEL RATIO SENSOR (BANK 1, 2 SENSOR 1) (See DTC P2195 OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 1 SENSOR 1), DTC P2196 OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 1 SENSOR 1), DTC P2197 OXYGEN (A/F) SENSOR SIGNAL STUCK LEAN (BANK 2 SENSOR 1), DTC P2198 OXYGEN (A/F) SENSOR SIGNAL STUCK RICH (BANK 2 SENSOR 1) )
NG: REPLACE AIR FUEL RATIO SENSOR

OK: GO TO NEXT STEP.
INSPECT HEATED OXYGEN SENSOR (BANK 1, 2 SENSOR 2) (See DTC P0136 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 2), DTC P0156 OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK 2 SENSOR 2) )
NG: REPLACE HEATED OXYGEN SENSOR

OK: GO TO NEXT STEP.

REPLACE THREE-WAY CATALYTIC CONVERTER (EXHAUST MANIFOLD LH OR RH AND FRONT EXHAUST PIPE)

NOTE: In the damaged bank, replace both the front catalyst and rear catalyst.

HINT: Hand-held tester only:

The ACTIVE TEST A/F CONTROL procedure enables the technician to identify a trouble area if malfunction in A/F sensors, front or rear heated oxygen sensors other than the catalyst converter, or the malfunction that indicates the actual air-fuel ratio extremely RICH or LEAN.
It is possible to locate the problem area by performing ACTIVE TEST A/F CONTROL (heated oxygen sensor or other trouble areas can be distinguished).

Perform 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 to ON.
3. Warm up the engine by running the engine at 2,500 RPM for approximately 90 seconds.
4. Select the item: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
5. Perform the A/F CONTROL operation 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 at maximum.

Fig 2: A/F Sensor (Sensor 1) And Heated Oxygen Sensor (Sensor 2) Output Voltage Chart

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

To display the graph, enter ACTIVE TEST / A/F CONTROL / USER DATA, then select "AFS B1S1 and O2S B1S2" or "AFS B2S1 and O2S B2S2" by pressing the "YES" button followed by the "ENTER" button and then the "F4" button.