I've owned my 1990 Deville for 2 years (285 km), and that pesky orange light had always been on. After doing some forum reading I decided to try and fix the problem. Well I have. No I did not remove the S.E.S. bulb. The E49 code indicates a problem with your Air Injection Reaction system. What this system does is divert warm air into the intake when the engine is cold, then switches to divert it to your catylytic convertor when the engine warms up; this helps the converter burn off hydrocarbons, and lower emissions. My car idled rather roughly from the beginning, but I attributed this to high mileage on a high compression high octane engine. My solution is this: new tune up parts including O2 sensor. If your idle still seems rather rough/low, what I think happens is that you end up with a low vaccuum situation. Since the A.I.R. valve is vaccuum actuated (see the little hose going into it) a low vaccuum situation means it doesn't get enough pressure to do its job. This is why whenever I would reset the light, it would stay off until I left the car idling for a few minutes, then it would come back on. First off, make sure you have no vaccuum leaks. Second off, a high mileage engine probably has intake gasket leaks, if you don't want to change the intake gasket, look at the front of the intake behind the idle speed controller. There is a little screw that controls your 'mininum idle speed'. Get your car completely warmed up, and adjust this screw until your idle seems reasonably smooth. It's hard to get at, but on the bracket that holds the ISC, there is a hole that you CAN work an allen key into. It's like playing a game of Operation, but you can do it. Once you have the idle smoothed out, you'll also notice that those little hesitations on soft throttle tipins will disappear as well. I just noticed today that my light isn't on for the first time in two years, and I was so amazed that I checked the bulb just to make sure it wasn't burnt out. If you do all this and the E49 is still on, the little electrical valves in the A.I.R. might not be working, it's easy to change with a scrapyard replacement.