how to check O2 prob
 

Is there any way to check if my O2 sensor is bad. My check eng lite isnt on but my gas mileage has been getting noticeably worse. Just wondering if there are any easy ways to check if a sensor is going bad or went already.

If it's bad then it would throw a code, if the CEL isn't on then there's nothing wrong with it. I would try doing a basic tune-up(spark plugs, wires, cap, rotor, fuel filter and air filter) and probably an oil change too. Maybe try changing your tranny fluid too. Also make sure your tires are at the proper inflation.

just put new coil pack / distributor/ plug wires this past summer. just changed the oil although this problem showed up b4 that. dunno if the fuel filter was changed b4 i got the car. Would a clogged fuel filter cause a noticeable difference in fuel mileage? I would think maybe some power loss or something but if it is clogged it just slows the fuel down on the way to the eng so gas would not be wasted. prolly change the canister out anyhow it likely needs it and that aint too expensive. air filter aint that bad. my car is exempt from emissions testing so the sensor has never been tested.

I would go ahead and replace your fuel filter, then get back to us. ;)

My understanding is that the O2 sensors wear out with age and start to react slower and slower to changes. They won't necessarily throw a code till they completely fail. This past summer the way I found out mine were bad was because I failed emissions, after replacing my O2 sensors my CO and Nox dropped by over 50% and mileage went up. Never threw a code but they weren't reacting fast enough. There is a way to test but you'll need two people as they need to be tested with RPM's at about 2500 using a multi-meter.