Service Engine Soon

The SES light on my 94 buick roadmaster comes on for 5 miles then goes off. It has a 5.7 LT1 engine with 62k miles on. What are the most common problems?

Step #1 is to read your Owner’s Manual to determine the purpose of this light. If it indicates the need for an oil change, that is easy to pursue. If it is not an indicator of the need for an oil change, then the light indicates a problem with a myriad of ignition or fuel system problems that affect performance, gas mileage, and reliability.

After reading the relevant section of the Owner’s Manual, you probably will need to have the car’s OBD I system scanned for trouble codes. Only by scanning for trouble codes can anyone properly begin to diagnose the problem.

Out of hundreds of possibilities, you want us to pick just one?!
It’s better for you to tell us what performance changes (problems) it’s been having, lately. Then, we can have a guess-off.

I tried my GM scanner. It won’t flash. Meaning i have a problem that needs to be fixed before my scanner will work.

Since i havnt owned it very long. it sometimes idles somewhat rough for short periods.

The little GM scanners sometimes don’t work on all '94 and '95 GM’s, especially the more complex ones like the LT1. Paper clips do the same thing and don’t always work. You will need at least the venerable Snap-On MT2500, affectionately known as “the brick” to scan your car. You’re probably going to have to take it to a real shop with a real scanner to pull the codes. AutoZone won’t be able to help you on this one, and the brick still fetches $800-1000 used on the tool trucks.