[MT-2500]

Never heard of a false code transmission shot deal on that code.

Code is for a 2-3 shift valve problem or curcit problem.

Get the solenoid from your chev parts dealer.
And when pan is down wirh key on confirm 12 volts power on red wire to solenoid.
Also make sure solenoid wire plug is pluged in good.
If 12 volts to it key on and pluged in good replace solenoid and give it a try.
May also be a good time to change transmission filter.

One word of caution when installing transmission pan be careful and do not hit or bump solenoids/the plugins on back solenoids.
May have to slide crossmember back to get pan off and on easy.
when done and full of fluid.
Clear codes and drive it.
Let us know how it goes.