Are you trying to read the code or reset the ecu? If your just resetting it and the light is coming back on then I'd suggest you need to read the code to troubleshoot. It's tricky to get the peddle dance right, keep trying. A search on here will give you a table for what the codes mean. If your stuck do you know anyone with an Obd2 code reader? I can get hold of one but I won't be anywhere near dungannon till the end of next week, if your still struggling then I can meet you.
R.