Check engine light stays on. Told sludge in oil but my oil light never went on.

Get 2nd opinion.

I have the same problem. I also have a 2008 Kia Sedona, I was getting the same codes and was told by the dealership that there was sludge. After a few tries at a few different KIA dealers to get this sorted out (the first dealership allegedly ran some engine cleaner through it) the second dealership did some preliminary tests before deciding it was no longer under warranty, I decided to drop the pan myself, october 13, 2012....found a lot of sludge. if you take out the engine, take it apart, it can be cleaned. Otherwise, the engine will probably fail.