code 80 is throttle pot (VR1) out of range
i would try and run a learn on the handle first and see if that cures it
if not then you will need to replace the VR1

Note: if there is allot of play in the spring detent and the handle has excess play in travel direction and keeps beeping allot when in neutral position and will not stay calibrated you may want to consider just replacing the handle complete with a reman handle. Repairing these handle assy's has proven to be not so cost effective unless its a simple fix like a VR , knuckle repair/replacement or switches or the circuit board in the rocker button is very time consuming and labor will cost as much as a reman before its all said and done.