It looks simple and DIY repair. So trying to figure out what part is bad and need repair.

My 2001 Nissan Altima SE,
Turn light Go OFF while the Switch is still ON. Sometime it doesn't even start when turning the signal down/up. Emergency light also has the same behavior.

Checked all the fuses under the steering section on driver side but all are OK.

What can be the problem? Is it the Turn Signal Switch, Flasher, ..?

Appreciate your help.

Replace the bulbs first. If that doesn;t fix it, sounds like a bad flasher, although a failed switch would do the same thing.

Thanks AZhitman for your response. Appreciate it.

It worked for couple days and started showing problem. Bulbs seems working so I thought to start with Flasher as it was cheap.

Looks like it has fixed the problem.