P0420

Test 1 - Test 6:

SYMPTOM
P0420-CATALYTIC 1/1 EFFICIENCY

WHEN MONITORED
Engine Run time greater than 90 seconds. Engine Coolant greater than 70° C (158° F) Vehicle speed greater than 20 MPH and less than 55 MPH. Engine Speed greater than 1216 RPM and less than 1952 RPM.

SET CONDITION
As catalyst efficiency deteriorates, the switch rate of the downstream O2 sensor approaches that of the upstream O2 sensor. If at any point during the test the switch ratio reaches a predetermined value a counter is incremented by one. One Trip Fault.

POSSIBLE CAUSES
- Good trip equal to zero
- Visually inspect catalytic converter
- Exhaust leak
- Engine mechanical condition
- Aging O2 sensor
- Catalytic converter