The car got check engine lite and code to repair was a tune up.didnt help

Hello, No "code" will tell you to do a "tune up". Never. Codes will provide diagnostic troubleshooting clues to help a technician find out what is wrong with your Cadillac. The onus of responsibility is on your technician to stand behind the diagnosis and continue testing on your behalf until finding the source of your issue. Or, conversely to explain to you why there is an additional concern present. Only with diagnostic testing can you know for sure what is failing and causing your warning light to come on.