S70 100k maintenance?

First make sure the wheels rotate freely after driving the car to make sure the brakes aren't hanging up. When spinning the fronts, don't mistake resistance from the differential for dragging brakes.

They're not regular maintenance, and usually (but not always) set a fault code when they're starting to go bad, but the front oxygen sensor can cause this.

Also I didn't notice any mention of the air filter. And there's nothing to adjust.

My owner's manual (for 2000 S70 indicates that timing belt should be changed at 105K miles. Don't know if that'd have anything to do with mileage or not. I'm coming up on that shortly, but my gas mileage hasn't changed.

Thanks Mike and mdrawson! I'm sure air filter and timing belt are not the concern. Air filter has been changed at 30k interval and the current one has been used for less than 10k miles. Timing belt was changed at 90k miles.

I don't think the brakes are malfunctioning to cause reduction of MPG. But I'll try to double check.

Actually O2 sensor is the one I'm suspecting. But there's no sign (like Check Engine light) for its going bad. Wonder if it's worthwhile just replacing it for a change.

I am also wondering about other things like a new set of spark plug wires (stock ones still used) or something else.

There got to be a reason. Not only the MPG has dropped significantly (more than 20%), I can also clearly feel that the horse power of my S70 is much worse than before.

I'll appreciate any thoughts or input.

Thanks. WHC

I have a '99 S70.

It gets about 29-31 on hiway, and about 24 in town.

j.

It's a bit hilly in my area. For instance there's about 900ft altitude change between work and home, though it's only 8 miles. So slightly lower gas mileage is expected. But my concern stems from difference between now and one year ago with the same style of driving.

Yesterday "Check Engine" light came up. Maybe something is indeed wrong. I'll try to find out what code it is by using my ODBII reader.

WHC