So my SES light came on a day after I got one of my tires replaced (was really worn out) as my girlfriend was driving the car, so I took it in to get it scanned. I forgot exactly what the guy said it was but he said it was a common problem with cadillacs and this engine in particular, some kind of general code 404 exhaust leak. It doesn't seem to be affecting anything for now since I'm still pulling a consistent 6.5-6.7 second 0-60 on street tires on my g-timer, and the car doesn't seem to be running any worse or getting any different gas mileage. However, the damned light is on and its irritating.

The guy who scanned it for me said it could be leaking just about anywhere and that I'd be better off taking it in to get it fixed. Problem is, I'm not sure if my warranty will cover it, and I'd rather not take the chance if I have to fork out a couple hundred dollars on my own, especially since I've had nothing but problems with this car since I bought it (blown coilpack assembly, broken temp gauge on gauge cluster, trunk leak, fog light wiring harness, steering shaft). If this keeps up, this will be quite possibly the most unreliable car I'll have used. It would appear that my tie rods are also worn out, which will cost me parts and alignment. I know its a premium vehicle, but this is a bit much in just 3 months.

Does anyone have any ideas as to how I might be able to check where this leak is occurring? Is this a common problem with a certain component?

From TECHINFO above:

"DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance "

It may be just that your EGR valve needs to be cleaned. I don't know where you git it scanned but your guy was pretty darned vague in his description to you.

You need to start by cleaning your EGR pintle and see if that fixes it.

You are right to want to fix anything that makes your SES light stay on. An SES light constantly on could hide a more serious issue in the future.

Let us know how it goes.

I went in and got it scanned again, and it was an error 0441 small evap leak. I changed the gas cap and it hasn't come on again after driving 200 miles.

Has GM cut down on its quality standards since 1995? I'm still using the original gas cap on my regal at 179,000 miles, and I have yet to have that SES light turn on for any reason at all.

More than likely....cost cutting in all areas over the past decade in order to make cars cheaper, lighter....even if it is only a penny, they will cut the cost.