P0700 on BMW: causes and affected models

ZF 6HP gearbox (3 faults), ZF 8HP gearbox (3 faults), BMW Serie 1 F20 (1 fault), BMW Serie 2 Active Tourer F45 (1 fault), BMW Serie 5 E60 (1 fault) and BMW X2 F39 (1 fault). Each fault has its own page with the affected years and versions, the symptoms and the repair cost.

Transmission control system (request to turn on the malfunction indicator lamp, MIL). P0700 is a "summary" code: the transmission control unit (TCM) has detected a fault of its own and tells the engine ECU to turn on the warning light. AutoDTCs describes it as a "gateway" code and Carista as a wrapper, and both agree that on its own it says nothing about the nature of the fault. The name of the standard varies by source: "Transmission Control System (MIL Request)" at AutoDTCs and "Transmission Control System Malfunction" at Mechanic Base and TaT. It is a generic OBD-II code: it means the same on a BMW as on any other make.^{[1][2][3][4][6]}

As soon as possible. The sources agree that it is serious. Autodoc Club says it is not safe and must be resolved immediately, because of the safety risk and possible engine damage, and its UK version recommends avoiding driving until it is repaired. Mechanic Base classes it as serious and advises you to stop driving as soon as it is safe to do so, because continuing to strain the car can permanently damage the gearbox. Carista and AutoDTCs give it high severity; AutoDTCs qualifies that, in limp mode, you should only drive to the garage, and that the car must not be towed with the code active. The prudent course is not to carry on using the car as normal and to take it to a garage as soon as possible.^{[1][2][3][4][5]}