Hey guys, I bought the car a few weeks ago with 75k from a covert ford dealer in austin, tx. Had a check engine light and bank 2 sensor 1 which cause cylinder 4 misfires so I changed out the o2 sensor and 500 miles later it fouls out again. The sensor is not carbon coated when I pull it so its running lean? Not sure what to do here, any help would be greatly appreciated guys

 

I would think the cylinder 4 misfire is what is messing up the O2 sensor, not the other way around.

 

Hmmm plug or coil?

 

Could be either, or a dirty/faulty injector.

 

Ok I'm taking it to the dealer this evening and will get back soon