I have 1996 Ford Explorer, V6, 84k miles.
A month ago I replaced the thermostat because it was running cold. The I replaced the air filter too. Two days later Check Engine light cam on. The car is running well, the gas mileage improved from 19.5mi/ga to 21.4mi/gal. The OBD code is P0420 (the catalyst efficiency for bank 1 is under th threshold).
Can anybody help me with this: Do I need to reset the OBD monitor? If not, how bad is it I mean do I need to see a mechanic ASAP?
Thanks Mi
-- Mig