Hi there! My 2004 VW Beetle has just been serviced about 2 weeks ago but sometimes when I switch it on, instead of there being the normal blue temperature light it is red, flashing and beeping and i'm sure this means the engine is overheating? I don't understand how it can be overheating if i'm just turning it on? I took my car back to the garage who serviced it 2 weeks ago for them to double check it and they said they couldn't find a problem with it. Should I be concerned or is it just a wee fault? Thanks!