This year did not pass emissions test in OR. o2 how many sensors 2 or 4? o2?

rec. fuel system clean. ethanol treatment to 1 tank premium. ethanol blend in fuel causes build up fuel system, combustion chambers, exhaust system and causes increased wear to spark plugs. build up can trip sensors.clean system burns cleaner. rec. periodically repeating. rec. oil stabilizer treatment with next oil change. recondition cylinders and seals. rec. every third oil change. review when last tuned. it may be due. if so rec. e3 spark plugs as replacement. bigger spark, cleaner burn. examine ignition cables for wear or damage. if need to replace, rec. upgrade to performance type. accel's are good and more cost effective than OEM replacement. performance grade ignition cables allow for more conductivity giving stronger spark(cleaner burn). rec. upgrade conventional air filter to high air flow design such as a K&N high air flow filter. these filters will allow engine to breath easier giving you slight boost in horse power and fuel economy. engine breaths easier, it burns cleaner. these filters will last 10 yrs plus provided given due care(once a year cleaning). save money long term on air filter replacements. these are all things you can do yourself, save money from going to a shop. good luck.