There's a very simple thing to check first: your brakelights. If they don't work, check the brake pedal switch. It's a common fault. Also have a look for anything obvious like a loose or failed HT lead, or an audible air leak if that's appropriate for your car.
Other than that, you really need to get your car scanned by someone with VAG-COM (VCDS), a VAS computer (the one dealers have), or a OBD-II scanner.
Of these, the VAS or VCDS/VAG-COM is your best bet as it can read and decode more faults from the car.
You have several ways of getting the car scanned:
* You can pay a Skoda (or other VAG) dealer. Typically this will cost at least ?40.
* You can pay an independent garage. This will be a bit cheaper, but unless the garage specialises in VAG cars, it will probably only have a generic scanner.
* You can ask here in the VAG-COM and diagnostics forum. Look at the member map. If there's someone near you, send them a PM, and negotiate a price- which may just be a pint or two.
* You could obtain VAG-COM/VCDS or a code reader yourself. This can cost as little as ?20ish for an ebay cable and a limited downloadable version of VAG-COM, but a fully licenced version (with full capability and support from Ross-Tech) costs more.
For later cars (Octavia II and Superb II), you need a CAN-capable scanner or a version of VAG-COM and appropriate genuine Ross-Tech cable that supports CAN-only cars.
A scan really is the only way to try to diagnose a CEL/EPC light, and often odd running problems as well. If you post the logs from the scanner on this site, someone will have a chance of solving your problem. Otherwise, it's just wild guesswork and you could be checking and changing things for ever.
Edited by cjb, 16 June 2009 - 16:03.