Early Production (SBEC)

Test 1 - 6:

SYMPTOM
P0420-1/1 CATALYTIC CONVERTER EFFICIENCY

WHEN MONITORED
After engine warm up to 70° C (158° F), 180 seconds of open throttle operation, at a speed greater than 20 mph and less than 55 mph, with the engine at 1400-2000 rpm and MAP between 13.0 and 17.8.0 inches of mercury (Hg).

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, the test fails and the code is set.

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