We have a shower pan that is leaking to one side (small leak by the step), 1st plumber said it was a caulking issue where the step tile meets the floor of the shower, 2nd plumber says it's the drain leaking because it doesn't have the appropriate FHA drain, we know there is an FHA drain in place and he did a pan test (covered the drain), which will lead us to believe that since the drain was covered the leak is not coming from the drain, he says floor needs to be removed and a new pan installed, any ideas?. how much will this cost?

If covering the drain, partially filling the pan did not leak then it is not the tile caulk. Did it start to leak again when the plug was removed from the drain, if so then it's the drain itself.

Sorry, it leaked while the drain was covered, water seeped from the side of the shower

Sorry, it leaked while the drain was covered, water seeped from the side of the shower
Something's not right here. You have a flange type shower drain, (see image) with weep holes in the floange to drain any water that should seep down out the trap and down the line. Unless the tile man allowed the weep holes to get clogged with tile grout they should handle any seepage that leaks down into the pan. Could you post a picture of your drain? Thanks, Tom

Then most likely your drain is not the issue but the pan must be cracked, not just a caulking issue unless its leaking unedr the door or something. Is the floor of the shower pan fiberglass or tile or what? Most pans can be repaired without doing a total tear out.

Is there a liner under the pan cement?

The floor of the shower is tiled and yes there is a liner under the pan cement.. I think the leak is coming from where the tiled floor meets the curb.. I am just preparing for worse case scenario, if the entire shower floor needs to be replaced

Unless this shower has been leaking from the git-go I don't thionk the shower floor will have to come up. The vreason being that showerv pans either hold water at the installation or you form them again. I've neverf had a pan go bad if it was installed correctly. Of course I can't vouch for preformed pans. I've never put one in. But it's unlikely. Not impossible but unlikely. My bet's on plumber #1 .as I don't see how a FHA drain would make any difference. Regards, Tom