check engine code P0603 alone

The code p0603 setting in the Powertrain Control Module of your 2004 Acura MDX is related to the internal Keep Alive Memory (KAM) of the PCM. On some vehicles p0603 can be set when the battery is disconnected but that will generally not turn the check engine light on. If your check engine light is on due to the code P0603 you may need to reprogram or replace the PCM to correct the problem. I don't find any service bulletins for your MDX related to this issue.