Poolsean knows more, but unless you hear from him, I'd recommend ignoring the salt test for now, and replacing some water to see if doing so lowers the salt reading.

If you replace 1/5 of your water, but don't see a change in the salt level . . . your unit probably has a bad salt sensor.

If you do see a change, lower the water till your SWCG thinks the level is OK. Once it does, see if it makes chlorine -- if it does, you're home free. If not, well then you've got an SWCG repair issue to address.

Ben
"PoolDoc"