Question

2008 Nissan Sentra 2.0L with code P1740. What does the code mean?

Answer 1

P1740 is a transmission-related Lock-up select solenoid valve. Your car has a CVT which had a lot of problems, so Nissan extended the warranty to "10 years/120,000 miles, whichever comes first." If you are under 120,000 miles they will fix the issue, by either replacing the valve body or the whole transmission for free.
http://www.nissanassist.com/ProgramDetails.php?menu=2

Answer 2

P1740 NISSAN Code - Lock-up Select Solenoid Valve Circuit
Read more: https://www.autocodes.com/p1740_nissan.html