The first thing I would check is for broken motor mounts. This causes the vibration around 40-45 mph. There is a service / recall bulletin about this at Kia.
There is no servicable transmission filter on the Sedona.
In transmission
I recently had the tranny fluid replaced by my trusted mechanic. He told me there is a replaceable metal screen inside the transmission that would require the trans' to be physicaly removed to be replaced. It wasn't worth the money for me so I didn't have it replaced. RHB 051809As far as I know, the Kia Sedona does not have a changeable transmission fluid filter. (I could find nothing to indicate that it has one at all.) Service procedure for the 2002 does not call for a filter to be replaced. I imagine it's the same for the 2003. That is correct! It does not have a filter!!!The Kia sedona Does in fact have a transmission fluid filter. As i have one. it is hard to find as we are still looking for mine. but they wouldn't not have sold me one and the fluid together if there was not one that was to be changed. ours is a twist on. it looks like an oil filter...Yes, the Kia sedona 2002 to 2003 do have 2 filters. One on the outside on top of the engine underneath the cover to the right. And one inside that one does not need to be changed. 2004 and up do not have 2 filters just one insde.
YES
The 2005 Kia Sedona has a 5-speed automatic.
The 2002 Kia Sedona has a 5-speed automatic.
The 2004 Kia Sedona has a 5-speed automatic.
The 2003 Kia Sedona has a 5-speed automatic.
It is inside the transmission case. According to Kia, the filter is only replaced during overhaul of the transmission. You have to separate the case halves to replace the filter. This trans has no lower pan.
The 2009 Kia Sedona has a 5-speed shiftable automatic.
The 2014 Kia Sedona has a 6-speed shiftable automatic.
The 2010 Kia Sedona has a 5-speed shiftable automatic.