The P0420 (whose official onboard diagnostic definition is ‘Catalyst System Efficiency Below Threshold’) code is a sign that a vehicle’s catalytic converter is subject to one or more problems. Such ...
with the 4.0-liter six-cylinder and about 120,000 miles. I keep getting a catalytic converter code P0420. I heard there may be a way to fix it by spacing the O2 sensor away from the cat and changing ...