engine light on in my 2005 mdx ,but the car runs fine checked the gas cap no problem

 

Hey arthur!
you'll need to have the check engine light read with an OBDII reader.
an auto store usually provides this service for free and will tell you what codes the car threw.
the codes are important because it gives us a starting point on what may be wrong with your MDX.

report back with codes!

 

Any word on this OP?