i have a 2008 honda odyssey then the malfunction light came on

you need to take the car to a part store to get the code or (s) that its putting out cause that could be from a bad gas cap to anything that has a sensor

I agree with luissixtyfive. You need to get the code checked. Also you can try taking off the gas cap and putting it back on and then starting the car. That was the problem with my truck.