In my manual (pub # G301BE 2 (back cover)) Throttle sensor, code 31 is on page 196 and 197 and lists engine OFF throttle closed as 4.4 to 4.8 and WOT as .7 to 1.7

If it was mis-set at 0.5 there was no indication. No check engine, or problems running (besides the flare)

My manuals are copyright 1991 so I'm hoping this was changed in a TSB?

Collins