Okay, so I took the new O2 sensor off today and found it to be totally black with a charcoal-type residue. I took the part to the auto parts store and the technician said that I have a bigger problem than the O2 sensor. He said that the engine is running too rich and the O2 sensor should be a light gray color instead of black.

I checked the service manual and it says to check the fuel pressure regulator but this requires a gauge which runs about $40. The part is only $60! Does it sound logical that the fuel pressure regulator is bad? I just checked the fuel economy and it is only getting 27mpg which seems low for a 1.5l engine.

Any suggestions? Is there another way to check the fuel pressure regulator without a gauge? Any advice would be great!