1997 Ford Contour, 100,000 + miles, no major problems.
About a week ago the car was in the transmission shop to replace a bad shift
sensor. At that time the mechanic said that one O2 sensor was bad and replace it
as well. The car ran fine for a while.
The check engine light came on yesterday and displayed the generic code "P0304"
on my ODB2 code reader (#4 cylinder misfire). I checked and replaced four bad
plugs. It still runs rough and again displayed the same code, only now I also
have Catalyst Monitor, Heated Catalyst Monitor, and Oxygen Sensor Heater Monitor
displayed. There is also a burning smell.
How many O2 sensors are there? Could there be another problem as well?
I'm a little worried since catalytic converters can reach temps as high as 3000
degree F and can start fires.