Inspection Procedure

WARNING: This page is about a different variant/trim than selected.

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)

Read the DTC using the hand-held tester or the OBD II scan tool.

Result:

DTC RESULT

Display (DTC Output)	Proceed to
Only P0420 is output	A
P0420 and other DTCs are output	B

HINT:

If any other codes besides P0420 are output, perform the troubleshooting for those codes first.

B: GO TO RELEVANT DTC CHART (See DIAGNOSTIC TROUBLE CODE CHART )
A: GO TO NEXT STEP.

CHECK FOR EXHAUST GAS LEAKAGE
1. NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT
2. OK: GO TO NEXT STEP.
INSPECT AIR FUEL RATIO SENSOR (BANK 1 SENSOR 1) (See INSPECTION )
1. NG: REPLACE AIR FUEL RATIO SENSOR
2. OK: GO TO NEXT STEP.
INSPECT HEATED OXYGEN SENSOR (See DTC P0136, P0137, P0138: OXYGEN SENSOR CIRCUIT (BANK 1 SENSOR 2) )
OK: During air-fuel ratio feedback, the O2S's output alternates between rich and lean.
1. NG: REPLACE HEATED OXYGEN SENSOR
2. OK: REPLACE BOTH FRONT CATALYST AND REAR CATALYST

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.

Connect the hand-held tester to the DLC3 on the vehicle.
Turn the ignition switch ON.
Warm up the engine by running the engine speed at 2,500 rpm for approximately 90 seconds.
Enter the following menus: DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F CONTROL.
Perform the A/F CONTROL operation with the engine idle (press the right or left button).
Result:

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume

+25 % --> rich output: More than 0.5 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 1: Injector Active Test Result Chart

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

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".