S4 V8-4.2L (BHF) (2004)
"EPC" is the abbreviation for Electronic Power Control, in other words electronic engine output control (electronic throttle).
When the ignition is turned on, the engine control module switches on the EPC lamp.
After the engine is started the engine control module checks all components relevant to the operation of electronic throttle system.
During the component check, the EPC lamp lights up for approx. 3 seconds. The lamp lights continuously if a malfunction is already established in the
course of this check.
If malfunctions in the electronic throttle system are detected during engine operation, the engine control module activates the EPC lamp. At the same
time, an entry is made in the engine control module DTC memory.