Cadillac Repair: Service Vehicle Soon Light, ngine, climate control

Question
What could cause this light to come on and stay on?This is A 1990 sedan deville,car runs just fine.Light has been on for 2 days,Manual says the computer could have a problem and the car should be taken in for service.What do you think ?

Answer
Hi Lebon, What you need to do is start the engine and then on the climate control panel push the off and red warmer buttons at the same time for aprox. 5 seconds or until it goes into diagnostics. Then on the fuel data panel write down all the codes that are shown and be specific about E and EE codes. Then turn the key off and the next time the ngine is started the dash will be back to normal. Once you get the codes repost what they are and I can try to determine what needs to be done to fix the car. Anytime there is a problem with a sensor out of range for the engine computor it will turn on eithor the sevice soon or now light depending on the code. Let me know what you find. Bill