BMW X5 E53 Automatic Gearbox Slipping and Fault Codes
What do fault codes P0700 and P0748 mean in the X5 E53 automatic?
P0700 is an engine management code that does not necessarily mean the gearbox is broken; a drop in battery voltage during starting can trigger it. P0748 points to the gearbox A solenoid: the cause can be poor wiring harness contact, a blockage, a low fluid level or the turbine.
Why does the X5 E53 automatic not shift when the car is warm?
The cause can be a temperature sensor or its wiring harness giving intermittent data, even if the fault memory is empty. Check the electrical connector and the wiring harness, and change the oil and filter.
Why does the X5 E53 4.4i ZF automatic slip in reverse?
The most common cause is the vulcanised rubbers of the reverse gear piston coming loose. The repair requires taking the gearbox apart, because the piston is the last part in the gearbox. According to ZF's instructions, the piston is replaced if the gearbox has been driven over 150,000 km.
What should be done before a gearbox repair?
Read the fault codes before the repair with a diagnostic tool that can access engine and gearbox data; a generic scanner may not show everything. Sometimes the fault is elsewhere, for example in a worn front propshaft when drive is lost.