Working on an Otis 211 which keeps giving me FLRP code (invalid floor position code) I've changed guides, even changed selector board, checked magnets, unit will work properly for 2,or 3 days and then shut down with FLRP fault, all needed to get it back up and running is a reset. Any suggestions

Is the car always shut down at the same floor or at certain floors? I had a 211 shutting down on FLRP a couple of months ago. I caught the FS1 led in the controller blink twice as the car leveled into the third floor. The magnet was dead centered and the guides had been replaced. I saw it do it a couple times running by the floor on car top but it would not do it at the 1st floor where there is also a magnet in that lane. It was the magnet! First time I ever had something come down to a bad magnet but after replacing it there was no flicker and problem solved.

I'm going to check that out tomorrow, customer doesn't know what floor it's shutting off at, I caught it one time on the 3rd floor as well but have never seen the led blink or flicker should I just go ahead and change it just to eliminate that possibility?

+1 on Dirts suggestion. The only question is, is the trouble AT the faulted floor, or the above or below floor, as the correction run starts in the direction of travel and the unit shuts down at the next floor in that direction. My issue was the third landing, but the unit would show the fault while landed and shut down at floor two.

Here at job now, car is overshoot intermediate floors by 2 inches then leveling itself out, it's a 4 stop unit

Is there anyway to do hoistway scan on Otis 211

Trader is not working right

Ok, try again;
You've ruled out valve issues? Magnets for slowdowns are secured? The 211 uses a non perforated tape, do I don't think a scan is available, and I'm not sure there is any adjustment in parameters for deadzone. Does the valve sound like it's allowing the car to slide through the floors with too long a transition?

Transition is ok, just car overshoots floors in up direction then relevels down, and keeps shutting down giving flrp faukt

Can you watch on the service tool or a PI that the car steps correctly at the slowdown point for each floor? Remember the slowdowns are binary coded so the car knows which floor it's running into. So if you watch the FS leds in the controller say send it from bottom to top. First yo should see the FS1 flash, then you should see FS2 flash 3 times ( up slowdown, floor level, then down slowdown) then you should see FS1 & FS2 flash 3 times for the 3rd floor, then FS3 flashes at the slowdown and comes back on when the car stops at the 4th floor. And it only overshoots 2 and 3 in the up direction? Not 4? Maybe a problem with FS2 traveler or input, its common to 2nd and 3rd floor. If that all checks out I would say maybe bypass is in too far but it would overshoot & relevel at the top floor too.

Two things:
1) If the unit is over shooting in the up only, and your transition is ok, I would believe based on your report, the selector IS seeing the slowdown magnets. LU is the question.
Visual inspection such as Dirt suggested would be helpful. IIRC, all magnet inputs can be seen from cartop.
2) Aren't there LED's for UL and DL on the selector head pc board? Verify these on cartop inspect. Does it level in properly to the top floor?

If it IS slowing, just blowing through the floors, maybe the up leveling adjuster is loose on the Maxton valve or just the UL adjustment (just thinking out loud here).
By chance do you know if the access up speed seems normal like 10fpm or so? That would give you a good visual on the true UL speed. Could very well be the selector head itself, but we don't want to jump there yet.