Cadillac Repair: Service engine soon, cadillac deville, service engine soon light

Question
My service engine soon light is on.  I own a 1990 Cadillac DeVille.  I have been told I need to replace the air management diverter valvue.  Another name I was given is I need to replace the Air pump switching valvue.  If we reset the computer the light will go out for two or three days.  Help

Answer
Hi John, I would get a second opinion on this one because there is a service bulletin that explains how to test the system and sometimes it winds up being the air management valve but othertimes it could be a weak AIR pump or faulty computor. If you take the rubber hose off the valve that comes from the pump and place your thumb over the end and then raise the idle to aprox. 2500 and if you get a strong force of air then it could be the valve but the computor needs to be tested to see if it is working properly. If there is weak air flow then you will need to put a pump on it first, clear the codes and then see if the code comes back. You may need a pump and a valve but without further testing you won't know for sure. Hope that helps. Bill