grantman18

I just picked up a 2000 Sport (stock) w/ 132k miles, and went through my first tank of gas. The average MPG was only 12.5. The split was about 50/50 city/highway, and I was in 4WD about 5% of the time because of the snow here in Boston. This mileage seems way too low, but I thought because of the cold weather and 4WD it might be normal.

I was fiddling with some fuses trying to debug a windshield wiper issue, and I accidentally pulled out the instrument cluster fuse. After replacing it, the check engine light stayed on. I thought this was just a fluke thing related to the fuse, but I thought I'd play it safe and visit Auto Zone and get the code read. I got a P0130 and P0136, which are O2 sensor codes (bank 1 and 2). Within an hour after getting the codes read, the check engine light disappeared.

Should I have my exhaust system looked at to see if the O2 sensors are bad? Everything appears to be original, so maybe it's due to be replaced? The car passed the MA emissions inspection (OBD) last week, but the muffler is pretty rusty and appears to have a few cracks. Could the muffler/O2 sensors be contributing to my low fuel economy?