What is alert 2.5h? - 2009 Nissan Altima

A bite alert is used for fishing and works to alert you when a fish is on your fishing rod.

Alert on what? Are you referring to a radar detector, navigation system, or something else? Have you checked the manufactuer's website of whatever device to see if there are updates? Often updates are slow to get distributed when it comes to navigation systems.

if he level is good the sensor is dirty or bad or the wires fell off

are you sure its level alert and not low pressure.
the operators guide tells you this, lost that?
get one.
low oil pressure is bad news
check it with real gauges. at the sender ,port , not guess.

should be a fuse in the fuse panel for door alarm simply pull the fuse out for the easiest fix

That sounds like a poor earth/ wiring short to me!

if ur looking for chime alert then at fuse panel is a round plastic chime that may be disconnected or needs replacement--if your looking for dash light then possible light is burnt or wiring problem under dash--

You can download a free owners manual from this site, it will identify all the dashboard alerts:
https://www.fleet.ford.com/maintenance/owners_manuals/results.asp

take auto zone have them test your computer codes for free see what gremelines inside ok

Call a dealership and just ask they will tell you. They want your business

Probably based on miles... Any dealer or competent shop can re-set the alert... Have them show you where it is so you know for next time (usually under the dashboard on drivers side but they move that stuff around so much, I can't tell you where it is exactly on your vehicle)