I had two Hayward Swimpure Plus T-cell 15’s that were reading around 1700/1900 when multiple tests show salt level at 3300/3400. Thinking the cells needed replacement I ordered the Pureline replacement cell for my Hayward Swimpure Plus T-cell 15. When I attempted to calibrate the cell it will not go below 4700. I had the water tested several more times and it’s still at 3300/3400. What could be causing this new cell to be reading so high? Yes, the board settings are correct with the exception of the cell amp reading a little high at 8.45.
I’m sorry to hear of the issue but glad that you double-checked the salt cell setting to be sure it is correct.
New salt cells tend to read a higher salt level but that’s a little too high. While almost anything is possible, it is more likely that the pool store salt test is wrong than that a new cell salt reading will be wrong. Pool store salt tests are very unreliable - I would recommend getting a good salt test kit and testing it yourself to get a truly reliable salt level. Remember that the SWG averages over 24 hours, so the reading of a brand-new salt cell will drift over 24 hours (if not the first week of operation) until it settles at a new reading.
It is common for old cells that are just starting to fail to read low salt when the salt level is actually fine. Some folks add salt based on the readings on the display so, by the time the old cell actually fails or gets replaced, the salt level can be quite high. The new cell will suddenly read the salt level correctly, and show it as being very high. If this is what happened to you the only option is to replace water until the salt level comes down to something more reasonable.
The other possibility (though this is a long shot) is that there could be a problem with the main board. These can have issues if salt is added at the skimmer while the SWCG is still turned on which can generate fairly high current and make some of the solder joints overheat and make a poor connection (the control unit assumes the salt level by measuring the current). If everything else looks good and if you are comfortable doing it, you may want to remove the board and look for connections that might have gotten hot. Look for brown spots on the board and reflow the solder to any components that look like they may have gotten overheated.
I’m pretty sure the salt tests were accurate as my salt tester was 3300 and the pool store reading was 3300/3400 over multiple samples.
Also, does a high salt level cause the cell amperage to be high (8.45), which isn’t excessive or can a bad board be an issue. I have no problem taking out the PCB board as I’ve had to make several solders to it over the years.
I trust your results way more than I trust the pool store. 
High salt levels do cause the high amps. If it gets too high your system will shut down and throw a trouble code or light, so I’m thinking this is just the result of a fresh new cell with good plating.
How long have you had the new cell installed?
I installed the cell about 24 hours ago
I would let it run for a week and check it. It should settle down.
It’s been a week and the instant salinity is at 4500. Several salt samples show the level in pool at 3000/3100. Still reading 1000ppm high and generator keeps shutting down due to high readings.