well the upstream oxygen sensor pre-heater failed in my transit connect

the strange thing is this is that fuel economy of this vehicle has increased by 22 miles per tank

( this vehicle was imported from the u.s , so the dash is in miles )

i can only gestimate that the pre heater was interferring with the sensor properly reading the exhaust emissions correctly

hmmm i may not replace the sensor at all if my fuel economy keeps increasing

i use only 91 octane fuel and i use the hottest motorcraft spark plugs ( AGSF52C ) in the winter

and the coldest plugs in the summer ( AGSF22C )

just a heads up