COMPONENT INSPECTION
Monitor the Catalyst Converter
Clear DTC.
Start the engine and warm it up until the radiator fan comes on (More than at least 10 minutes ).
Drive at a steady speed between 45-55 mph (72-88 km/h) for 30 seconds .
Stop and then maintain idle state for 120 seconds in D-position.
Repeat step 3 once again.
Stop and then keep it in idle state (D-position) for 120 seconds .
Repeat step 3 once again.
Stop and then maintain idle state for 120 seconds in D-position.
IG "OFF"
Repeat steps 3 through 9 three times.
Check if catalyst monitoring readiness is complete. so, if the readiness is incomplete, repeat steps 2 through 10.
Does the scan tool show DTC P0420?
YES - Substitute with a known - good Catalyst Converter and check the signal waveform of HO2S for proper operation. If the problem is corrected, Go to "Verification of Vehicle Repair" procedure.
NO - It was intermittent failure.