With a scan tool.
You need to have a diagnostic meter to read the codes, then book to tell you what they mean.
You use an OBD scan tool.
turn your ignition to the on position then off. do this for a total of three times, on the third time leave ignition in on position and look at your odometer. your computer will show up to tell you why your check engine light is on.... then search and find out what the codes are.
if you have the box with the digital miles try turning to key from off to on 3 times and on the 3rd turn keep it on and it should show. if not, refer to the vehicle manual. it should tell you in there.
Either with a scan tool, or by cycling the key on, off, on, off, on and counting the blinks of the check engine light. Two blinks, pause, one blink would be a 21.
http://www.autofixworld.com/index.php?option=com_content&task=view&id=379&Itemid=84
To remove the door panel on your 01-06 Dodge Stratus you would first need to remove the door panel. Then there are two bolts that hold the mirror to the door. You will need an 8MM socket or wrench to remove these from the mirror. I have included an instructional video below that walks you through this entire process. Hope this helps. 1aauto.com
with a scan tool, 97 neons are OBDII so they will talk directly to the scan tool. try a parts house has most will read codes for free
a junkyard
I would recommend purchasing the serivce manual for that car. it will contain the exploded views, as well as proper adjustments, fluids, etc. that will be required upon repair.
It is at the front of the engine in the rear underneath. GoodluckJoe It is under the passenger side fender weld,almost hidden from view from the plastic trim. its basically behind the front passenger tire