Where is the MAP sensor on a Honda Accord? Can my husband change this himself?

Depending on your Accord, it's located either on the top of the throttle body or on the firewall. If it's located on the firewall, look for a vacuum hose going to the throttle body. Your husband can easily replace the MAP Sensor in 2 minutes.

Thank you, it is an 04 accord EX. Do you recommend buying the part from Honda or will any MAP sensor work?

Honda usually uses Denso MAP Sensors--shop around for one and you can likely save some money.