About the only thing you can do is to purchase the OBD-II code reader. Here in the US, AutoZone auto parts stores will scan a check engine light for free. I recently had the code P0116. After researching it here on the BB, I found that the most likely cause was a thermostat stuck open. I bought the new thermostat and O-ring for about $12 US and changed it myself. I went back to AutoZone, had them reset the light and it hasn't come back on since. Being there in the UK, if you bought the code reader, it would probably pay for itself over time. Just my .02