Tuning the Mercedes C63S 4.0L Bi-Turbo can yield some pretty impressive gains. The only way to flash this ECU is on the bench. Mercedes however made it quite difficult to access this ECU compared to other Mercedes platforms. It is located on the USA Passenger side between the frame rail and the engine block. The ECU can be removed for flashing. Here are some instructions on how its done. Step 1: Remove the plastic under trays Step 2: Remove the two E10 bolts that retain the wiring harnesses to the ECU bracket Step 3: Free the two coolant lines from the plastic clips attached to the front of the ECU lower front bracket Step 5: Remove the E10 bolt from the front of the lower front ECU bracket Step 6: Disconnect both of the electrical clips that are that are plugged into the ECU Step 7: Slide the ECU forward slightly to access the 4x T30 Screws that retain the the front and lower ECU brackets Step 8: Remove both front and lower brackets from the vehicle Step 9: Carefully slide the ECU Forwards into the fan while turning it 90 degrees to slide the ecu out between the radiator and engine. Becareful not to damage the fan or the coolant reservoir while removing the ECU from the vehicle. Step 10: Send it to Vivid Racing for an ECU Flash – See Product Details Here Leave a Reply Cancel ReplyYou must be logged in to post a comment.