My 02 CRV Ex Awd has 103k miles on it and lately it seems to be getting worse gas mileage then usual. I tried doing all the usual things like changing the air filter, changing the spark plugs, checking tire pressure, checking for a locked brake caliper, fuel injector cleaner in the gas......etc. The car runs fine otherwise, it idles smoothly and has plenty of power it's just that the mileage has gone down about 4mpgs. So I plugged in my scan tool and everything looked fine there were no trouble codes but I did notice something strange with the upstream O2 sensor. Most cars I've seen the upstream O2 sensor switches rapidly from about .1v(lean) to .9v(rich) but mine is staying right around .620-.670v at idle as well as at 2k rpm. If the O2 sensor was bad it should set a code but I've read that they can become "lazy" or "biased" when they get old and it may not set a code. Does anyone know if this is a normal reading for the K24 engine? Any help would be greatly appreciated.