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Engine Control unit removal instructions (CAS removal down below)
The Engine Control unit (DME/ECU) is located on the outside Passenger side under the hood. Release all and locate the 2 plug DME / ECU. Pull the DME / ECU into the Upwards position then release both plugs sideways. (See Instructions & Picture Below)
1. Remove the driver’s side air conditioning filter cover. The air conditioning filter cover is a triangular box located right in front of the firewall. Three 8mm‐hex screws hold it in place. Two screws are located at the top corners, and the third is located at the bottom.
2. Remove the passenger’s side air conditioning filter cover. The passenger’s side filter cover is the same shape as the driver’s side filter, and is also held on by the same three 8mm‐hex screws.
3. Remove the rain gutter tray. This tray is located underneath the two air conditioning filter covers removed in (1) and (2) above. The tray runs the entire width of the engine compartment. The tray is held on by two 8mm‐hex machine screws.
- A. Remove the three screws holding the air filter cover in place.
- B. Once removed, the filter cover will still be attached by an air temperature sensor. Leave the sensor attached, and just rotate the filter cover out of the way – leaving the master cylinder brake reservoir exposed.
2. Remove the passenger’s side air conditioning filter cover. The passenger’s side filter cover is the same shape as the driver’s side filter, and is also held on by the same three 8mm‐hex screws.
- A. Remove the three screws holding the air filter cover in place.
- B. Once removed, the filter cover is still attached by an air temperature sensor. We will remove this sensor.
- C. The air temperature sensor is held on a rotating lock fixture, and two compression tabs. Rotate the sensor until it unlocks and remove it. Then follow the wiring and remove the two compression tabs holding the wiring in place. You may need to slightly pry these compression tabs to get them removed. The white box below is where the ECU is located. DO NOT PULL ON THE WIRING to remove the compression tabs.
3. Remove the rain gutter tray. This tray is located underneath the two air conditioning filter covers removed in (1) and (2) above. The tray runs the entire width of the engine compartment. The tray is held on by two 8mm‐hex machine screws.
- A. Remove the two machine screws holding the rain gutter tray.
- B. Remove the four rubber tabs holding the tray in place.
- C. Remove the tray. The tray will slide out. It may hit the engine hood struts. Just manipulate the tray until it is completely removed. The white box underneath this tray on the passenger side contains the ECU.
4. Remove the white ECU compartment cover. This cover is held on by two sliding locks, and four locking tabs.
5. Remove the ECU wiring harnesses. Each ECU wiring harness is held in place by a sliding lock. Pull each sliding lock and remove the wiring harnesses.
6. Remove the ECU. The ECU is held in by two plastic tabs. Pry these tabs loose, and remove the ECU.
- A. The white ECU compartment cover contains icons indicating a locked and unlocked position for these two sliders. Slide the two locks towards the unlocked position icon.
- B. Release the four locking tabs. You must reach underneath the ECU cover and pull the corner of each tab outwards until it unlatches. It’s best to use two hands for this: one hand to pull the tab outward, and the other hand to pull the locking tab bar upwards to remove pressure on the locking tabs. The pictures are intended to show where the locking tab bar is located, not the method for unlocking them.
- C. Remove the ECU compartment cover and expose the ECU compartment.
5. Remove the ECU wiring harnesses. Each ECU wiring harness is held in place by a sliding lock. Pull each sliding lock and remove the wiring harnesses.
6. Remove the ECU. The ECU is held in by two plastic tabs. Pry these tabs loose, and remove the ECU.
Removing the Car access System (CAS) from your BMW E90
