5L40-E Archives - Transmission Digest
Identifying the 5L40-E and 5L50-E Transmissions and Valve Bodies

The 5L40-E and 5L50-E transmissions and valve bodies look the same at a glance. On the Cadillac, Pontiac Solstice and Saturn Sky, you can look on the service-parts identification label to identify the transmission by the RPO (Regular Production Options) number.

BMW X5 Short Circuit

Doing electrical work can be interesting at times, and you never know what you will discover to be the cause of the problem. For example, a customer brought us his 2001 BMW X5 with the 5L40-E automatic transmission in failsafe. Another shop had worked on the engine and told him that the problem was with the transmission. When we checked for codes it had multiple codes in the engine control module (Figure 1).


As valves and bores begin to wear and allow leakage, the easiest path for the leak is to exhaust. Two things happen as a result of this wear-induced exhaust leak. First, the leak allows a pressure drop, which is loss of control pressure. Valves or components no longer move, apply or respond as intended. Second, the amount of exhausted fluid and, therefore, the amount of air entering the sump are increased. The amount of aeration can easily surpass the sump’s ability to dissipate the air before the pump picks it up. The minimal sump capacity of the 5L40-E makes it especially vulnerable to this problem.