This question already has an answer here:
I have a 2002 Nissan Sentra SE-R with a P1490 Code. What's wrong with the car?
This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
The OBDII system on your vehicle has an EVAP sub-system. The EVAP system vents the fuel tank fumes to the vehicles inlet manifold and are burnt by the engine. This prevents HC's being released to the atmosphere. The system will have a vent valve, purge valve, charcoal canister, control valve and hosing with its associated wiring to operate the valves. P1490 is an indication that the control valve is not operating correctly. You need to check the operation of the system. The easy way is with a bi-directional Nissan scanner, repair shop. The scenic route involves a full inspection of the wiring and components and jump wiring the valves with an external voltage to check operation, NOT recommended unless you are totally familiar with the system and the fire risks.