Service engine soon light comes on.

Gas tank cap is in perfect condition, no cracks, splits, or damage of any kind. No engine code. Just the instrument panel light that reads "Service Engine Soon" According to the manual, the gas cap needs to be retightened. Tried this many times before and the light goes off. Now, the light stays on after repeated retightening.

if the service engine soon light is on,and not the check engine light.it may be telling you that it is time to change the oil.but i may be wrong.service and check light may be the the same light,if so get codes read at az,adv,orly and post code if any.

Pardon my ignorance, but what is az, adv, or orly?

autozone,advance,oreilly autoparts.if the check engine light is on,there should be a code or codes stored in the computer.usually when check engine or service engine light comes on,there will be a code.if the maintenance light comes on,usually it means the oil needs to be changed.the parts places will check for you.its free,get them to print out code or codes,and post codes here.

Auto parts man ran a computer diagnostics test and found code 442. Does gas cap, evac canister and/or purge valve, and hoses sound about right? If so, where would the evac canister and purge valve be found?

ok,the code reader pulled a PO442.small leak detected.a loose or missing gas cap will cause this.if for some reason you didn't tighten the cap after re-fueling,it will trigger the light to come on.if,it was that,and even if you tightened it,the light just don't go off.go back to autozone,have them check it again,if same code,ask them to clear the code.if the light stays off,problem solved.if it comes back on,you have to start looking for a vacuum/fuel leak.do you smell fuel?copy and paste link OBDII Code P0442 NISSAN - EVAP Control System Leak ... www.nissanhelp.com/diy/obd_codes/p0442_nissan.html