M3 DME Removal:
Pick or flathead screwdriver with 90° head
The engine computer is located under the black plastic covers on the passenger side of the engine bay, against the firewall. To properly get to the computer you will need to remove all of these plastic covers from the top and both sides of the firewall. Most of these covers snap together or are held in place with 8mm screws. If you first remove the top panel immediately behind the passenger-side strut tower you will be able to see the computer compartment beneath it (white cover). Unfortunately the white cover cannot simply be removed without first removing the many black plastic covers on top of the firewall.
1. Disconnect the air temperature sensor perched just behind the strut tower (it just un-snaps).
2. Then remove the 8mm screws holding the large black plastic cover on top of the firewall. This cover runs along the top of the engine from one side of the car to the other and also houses the A/C system's microfilter. Completely remove this cover and set it aside.
3. Next there is a black, plastic cover behind the passenger strut tower. There are short rubber tabs sticking up from the cover that just "un-snap" from the rest of the cover assembly (remember to fasten these back at the end because this is part of the drainage system to keep water away from the engine computer!).
4. Repeat the process for the other side of the car with the cover over the brake fluid reservoir.
5. On the front of the firewall is another tray that runs the wiring harnesses over the top of the engine. Unsnap the top of this and use the 90° pick to separate the wiring tray from the bulkhead tray.
By now you should have the white compartment behind the passenger strut tower completely exposed. This is where the engine computer is housed.
6. Unsnap the 4 locks on the sides of the cover and remove it. Inside you will see 1 or more computers. There is only 1 DME with the two large plugs.
7. Unclip the wiring connectors running over the computer so you can get easy access to it.
8. Once you have clear access, unlock the two connectors on the computer itself by pulling their slide locks away from the center of the DME.
9. The computer is held in place with simple tabs - carefully pry the tabs away from the computer and pull it straight up and out of the compartment (be careful not to tug or catch any of the other wires in the compartment).
10. When the computer is completely free from the connector/harness, place it on a dry, clean, static-free spot (a piece of cardboard or thick paper). It would be ideal if you immediately placed the computer into the anti static material you will use for shipping.