The removal of the 991.2 GT3 ECU is fairly straightforward and can be accomplished with a basic set of hand tools and a set of torx bits.
Torx bits and sockets needed:
If you have any questions along the way please feel free to reach out to M-Engineering for help. Info@M-Engineering.us
Please disconnect the negative terminal from the battery before removing the ECU. Leave the battery disconnected as long as ECU is removed. For instructions on how to access the battery consult your owners manual.
Open up the rear deck lid
2. Begin by removing the fan shroud, this should pop up with little to moderate effort.
3. Remove the fans, they can be pulled out of their mounting grommets with little effort. There is a two wire connector on the back of each. Disconnect this as well and set the fans out of the way.
4. Now we can begin to take off the carbon engine cover. Begin by loosening the coolant and oil caps. Then remove the following bolts. You will need a T25, T27, and T45 for these. Two T45 bolts are hiding under the little black caps that should pull off with little resistance.
T25 - Circled in Green (4)
T27 - Circled in Red (4)
T45 - Circled in Yellow (4) - Two are underneath the black caps that should come up easily.
5. You can now start to pull the engine cover off. To make this easier you can remove the rubber seals from the inlets that allow in air from the deck lid (in orange).
You will want to lift the engine cover from the front. Getting it past the inlet can be slightly tricky but some minor messaging you should get the cover off easily. We began by lifting the left side where the oil cap is first then working on lifting up the other side. Once the front part of the cover is clear of the inlets slide it forward to release it from the rear bumper cover. There is a connector on the underside of this cover, disconnect it and set the cover aside.
On the underside of the engine cover is a connector for some of the rear end electronics. It is easiest to disconnect if you remove it from the mount first. This can be done with a set of pliers.
6. Now that the Engine cover has been removed we can get a better idea of the engine bay, and where things are located. We will want to remove the right side inlet to get better access to the ECU (in orange). This can be done by grabbing the forward part of the inlet (red) and pulling it towards you. It may take a bit of effort but it will pop out of the bottom of the air box and it can now be removed.
10. Now we can finally get to the ECU, above circled in red. It is attached in the engine bay by two 10mm nuts that will require a deep well socket to remove. There is one on each side of the ECU pictured below. You can also remove the harness to get better access. There are two connectors that need to be disconnected. Simply pull up on the part that is circled in blue and this will actuate the slider to push the connectors off the ECU.
11. The final step involves disconnecting the ECU case from a small line and harness. The line, pictured below in red, can simply come out of the bracket if pulled down. The other harness attached to the plate, in orange, can be slid down and off the ECU bracket in a downward motion. Alternatively you can wiggle the ECU out to give you more access to that wire loom retainer.
Once everything is removed you can then slide the ecu out towards the back of the car and pull it from the engine bay!
Installation is the opposite of removal. Please remember to keep the battery disconnected when the ECU is not installed otherwise some faults may appear after reassembly.