Rough Idle, Check Engine Light on

2003 Cadillac DTS with 66k miles on it located in Florida. The car just started idling really rough about a week ago, then a couple of days later the “Service Engine Soon” light came on. When I first start it up it seems fine, even driving it for about 5 minutes, but then after that it starts idling rough - really noticeable when at a stop.

I’m not a mechanic and I need to take this somewhere to get it fixed. I’d like to get opinions on what it might be so I could have an idea on what to expect. I’m a complete idiot about vehicles so if I get to the wrong shop then I could end up with a complete new engine, transmission, and seat covers.

Any ideas??

Call around to a couple of auto parts stores such Auto Zone. Some will connect a code reader for free and pull the codes that caused the Check Engine light to come on. Once you know the codes, then from there you can determine where the problem might lay.


Agreed. This is exactly what anyone should do whenever the SES light comes on.

Most likely you will need to merely replace a sensor or a solenoid, or other simple component. The codes will let you know if later a mechanic is trying to sell you unnecessary work.

Thank you both! I’ll definitely do that first and will keep my fingers crossed that it’s something not too major. Great ideas!