Nkakamasembe makes some incisive comments re OBD codes – I would add that should you purchase an OBD scanner, such as the one linked above, displayed codes should be treated with caution. My advice would always be to clear the error codes – should they return, this might indicate a genuine problem.
Others have reported paying £30 for a garage to read the engine fault codes (or £130 to read & clear them) – my advice is that anyone owning a year 2,000 vehicle or newer should have access to an OBD scanner. As soon as reasonably practical, once the engine check light is illuminated – read (understand) and clear the fault codes.
Cheaper versions of OBD scanners are available (to the one linked), but it appears to have quite an advanced graphics display, able to give a graphical representation of data – rather than just numbers.