My Check engine light came on last night the dash display says it is electrical. Should I worry? The engine seems to be running smooth. I just got the car. What is the best tool to use to diagnose the problem. I also just had the battery replaced the same day by a dealer. I couldn't find the security code, but the dealer got that working also. Is there a dealer master key code they use or should it be written down somewhere in my manuals? Thanks!... Indy