Oldsmobile/Buick Repair: Intake Manifold - 1999 Buick Regal, vacuum gauge, buick regal

Question
Just replaced the plastic plenum on my Regal due to leaking coolant.  There was coolant on the manifold and in two of the cylinders.  We kept turning the engine over several times a day for several days before the repair was made.  The engine started, but I'm getting a rough idle.  Service Engine light is still on.  Spark plugs were not changed.  Need to change oil, slight coolant possible in oil.  Any suggestions to correct rough idle.  Also, how can the service engine light be reset?  Thanks

Answer
Hello Donna,
I would at least remove those two plugs and check them, but sounds like a good time to replace them all and change the oil.

While the plugs are out, crank the engine over several times to see if there is still coolant in the cylinders, although if it started, it should have blown all that out.

But get that oil changed soon, and since you ran the engine before changing it, I would change it again relatively soon, to remove any coolant pumped through the oil system.

I have heard some people say the codes can be cleared by unhooking the battery for fifteen minutes, but I believe that a scan tool is needed for cars later than 95.

Some parts houses will connect a scan tool, and read and clear the codes for you, especially if you get parts and supplies from them.

If the rough idle persists, I would connect a vacuum gauge, and see if there might be a leak in the gaskets, or a missing/split hose.

Van