Hello,

I had this check engine light on my S500 and fixed it. Through my research, people have replaced o2 sensors, spark plugs, air pumps, throttle body, and air check valves. I had this check engine light over one year, and I have replaced most of the items listed above by myself and finally fixed the problem. The problem was with the air pump, after I replaced it everything I have never seen the check engine light on again. You should take it out and test it, just add positive and negative, it should blow wind.