service engine soon, warning light on 2004 Nissan Murano

The warning light for "service engine soon" comes on and stays on. I took off the gas cap and tightened it several times. It's been a week now..

2 answers
You'll need to get the codes read out to see what caused the light to come on, otherwise it's hard to know where to start.
more than likely your fuel sensor...cost about 400 to repair