Honda civic 2006 and was left in a flooded parking basement.Do i need to replace the
 

engine?

Depends how deep the water got. If it reached the height of your steering wheel then the chances are that your engine will be wrecked. Sorry.

How deep was the water? Your insurance may just declare it totaled.

If there is no water in the air intake then it could well be OK. Dry it out before you crank. If there is water and it gets sucked into the engine then the cylinder head could go bang.I've seen a car cough water out of the exhaust then it started and the water had been up to the top of the gear lever.

if there was only water in the basement, no, a thorough cleaning will do. drain oil, pull plugs and hand turn engine to see if water got into the cylinders, change filters; HOWEVER, flood waters are seldom that clean. there is dirt and slime and all sorts of junk that can get into the engine so a thorough tear down and clean might be in order.

As long as it wasn't running when it went under there's chance. Before starting the engine needs to be dried out. The oil and fuel systems drained allowed to dry and refilled. Don't even think about trying to start the car till this has been done. If the car hasn't been under water too long there's a good chance it's salvageable.

Not Necessarily. I would say it depends on how long it was under water. If it was under water for weeks I would say you probably need to. If it was there for a short time it might be okay. The first thing I would do is drain the oil and gas. Put in new air and fuel filter. Put in fresh gas and oil, and see if you can get it started. If it starts I would drive it, and do several oil changes 100 miles at a time trying to flush out all the water. Also it would be a good idea to change your transmission fluid. Have you talked to you r insurance company? They might pay for any repairs.