?Service Engine Soon Lamp (MIL) On with DME Fault 120408 Stored. The Service Engine Soon lamp (MIL) is illuminated with a reduction of engine power. Fault 120408: Charging pressure control: Switch-off, pressure build-up blocked is stored in the DME. CAUSE 1. This fault normally sets as the result of a problem with another component of the engine management system. 2. When there are no faults, the vehicle voltage might drop momentarily below the threshold of 9.985V, typically during an MSA engine start. This could result in the charge-air control being switched off.
