Why your Nissan xtrail is hard to start and the MIL is on while engine is running?

Retrieve the code that is causing the MIL to illuminate and you will be pointed in the right direction. There are thousands of different parameters being monitored by the car's computer so it is impossible to guess which one is causing the MIL.

Any auto parts store (Autozone, Oreilly, NAPA, etc.) will connect to your OBDII port for free to retrieve the code for you, and you'll have a gearhead that may be able to give you advice and help you diagnose the problem, also for free. A garage may and a dealership WILL charge you to retrieve the code, and they sure wont tell you how to go about fixing it.