Have a 1994 Cadillac Sedan Deville recently changed spark plugs. Now service engine soon light is on Why is light on ? Car runs rough?

Sounds like you 've got the plug wires crossed in the rear, it's easy to do. You can call me me at work, 501-224-2338, Parham West Exxon, I'm Neal. It's alot easier to explain, on the phone. I can't type enough words, to explain it to you.

crossed plug wire,plug you cant get is on back,right,get to it from under the car.google the fireing order for your car it will show you which wire goes to what plug.

Check your firing order. Your owner's manual should show the firing order for that particular Cadillac. If two wires are out of order it will run bad, and if you get it started it will use a lot of gas, at $3.50 a gallon.

Change that one plug before you do anything and in addition to the answers one and two also insure the plugs are firmly in place. Been there and did NOT do that once or twice.

also check make sure ur wires are snapped on the plugs good

Will a bad spark plug cause your car to stall and lose power and make a backfire kind of noise

I have changed the catalyst converter, alternator,starter and battery....my car still stalling and losing power..can somebody plzs tell me what my problem is...ibdone spwnt to much money on my car and its really frustrating