Inspection Procedure

HINT:

Read freeze frame data using OBD II scan tool or hand-held tester. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

1. Are there any other codes (besides DTC P0420) being output? 
   1. YES: Go to relevant DTC chart (See  DIAGNOSTIC TROUBLE CODE CHART  ).  
   2. NO: Go to next step. 
2. Check gas leakage on exhaust system. 
   1. NG: Repair or replace. 
   2. OK: Go to next step. 
3. Check A/F sensor (bank 1, 2 sensor 1) (See  INSPECTION  ). 
   1. NG: Repair or replace. 
   2. OK: Go to next step. 
4. Check heated oxygen sensor (bank 1 sensor 2) (See  INSPECTION  ). 
   1. NG: Repair or replace. 
   2. OK: Replace three-way catalytic converter (See  THREE-WAY CATALYTIC CONVERTER (TWC) SYSTEM  ).