My girlfriend has a 54-plate Seat Ibiza and it recently let her down on the way to work. As she was driving, the EPC light on the dash lit up and the car wouldn't rev above 1500rpm under load. Looked it up in the handbook and it said that EPC is an "accelerator pedal fault" and to take it to a Seat dealer immediately. Not likely! Left it to stand for a while then took it into my mates garage - the diagnostics wouldn't give an error, even though the EPC was lit up on the dash, so drove it around for a few minutes until it did it again.
Turns out the brake light switch was at fault, and the ECU forces the car into a "limp-home" mode, but actually creates a more dangerous situation than having no brake lights!
Apparently it's fairly common for these switches to fail - my Dad had one go on his Audi A6 a few years ago, and Dave the mechanic said that he's replaced several. So if anyone gets an EPC warning light on the dash of a reasonably new VAG car, might be worth spending just under £8 for the new brake light switch before sending it in!
