Terrible gas mileage in 96 civic
 

My gf's 96 civic cx is getting terrible mileage. shes getting just over 250kms a tank and it costs her roughly 40 to fill. I recently changed the plugs, cap, rotor, fuel filter and put on a cold air kit which helped a little bit maybe an extra 25kms a tank.

Im thinking the catalaytic converter is plugged or her fuel pressure regulator has gone south. Anyone have any ideas?

The converter on her car is a one piece design that bolts directly to the cylinder head so checking it would be pretty tough.

you can remove the front o2 sensor to have a peek in the converter. If its a higher milage car with original o2 sensor, i would consider replacing the o2 sensor

Her O2 sensor needs replacing. I'm almost 99% sure that's what the problem is. If the CAT was clogged you would notice a significant loss in power and you would get smell in the car from the exhaust not venting properly.

Berz out.