BMW reports if a transmission fluid leak appears to be traced to the transmission oil pan area, inspect the Mechatronic sealing sleeve’s O-rings.
Drain and save the long-term transmission fluid (Shell M-1375.4).
Replace the sealing sleeve (P/N 24 34 7 588 725) and the transmission oil pan gasket. Follow Repair Instruction RA 24 34 020. Make sure to push the sealing sleeve firmly into the housing assembly before closing the white locking tab of the Mechatronic. To ease the sleeve installation, apply transmission fluid on both sleeve’s O-rings.
After installation, the correct distance between the transmission harness connector and the housing surface should not exceed 3mm. When installing the transmission harness connector, do not use excessive force. Locking of the connector should not require an increased effort. This would be an indication of an incorrectly installed sealing sleeve.
If the distance between the connector and the transmission housing (A) measures approximately 7 – 8mm, the sealing sleeve was installed incorrectly. In this case, an intermittent connection problem between Mechatronic and the vehicle harness connector will occur, resulting in various EGS communication faults (for example: FC 5079 “Serial wire message missing”; FC 507A “Serial line signal plausibility”; “Gearbox Emergency program” light illumination; and the transmission entering a failsafe mode).
In some cases, the incorrectly installed sealing sleeve may permanently damage pins in the Mechatronic connector (X8500). If this happens, the Mechatronic module must be replaced (pin repair is not possible).
Clean the groove in the plastic oil pan before gasket installation. When reinstalling the pan, make sure that the sealing surface of the gasket is oil-free. If not, a leak may occur.
On transmissions equipped with a plastic oil pan (all with the exception of the E53), replace the drain plug. Follow the drain plug torque specification from RA 24 34 020.
Top-off the transmission fluid using Shell M-1375.4 (P/N 83 22 0 142 516). Warm the engine and test drive to verify.
NOTE: According to BMW, in the unlikely event that the transmission fluid leak reappears in the area of the oil pan gasket, the transmission oil pan and gasket must be replaced.