How do i turn error cord light off on a kubota L3901 tractor

E-20 CAN Communication short-circuited. Check the communication line. Check the main ECU connector.

Look for physical abrasions or rodent damage along the harness leading from the engine control unit.

Only result I could locate using https://www.google.com to search for error 83.

https://www.tractorbynet.com/forums/kubota-owning-operating/225670-error-83-gl3240.html

Communication failure "CAN bus error"

Tractors are no different than autos now... several computer controlled modules talking. If you stowed it with out cleaning out field trash, check for mice damage.

2nd attempt to answer. EGR valve overheating.
Refer to following link for discussions.

Engine Error Code Page 3 OrangeTractorTalks Everything Kubota

Good luck.
Semper Fi,
Z

this link might help you out.... https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=l6060%20kubota%20tractor%20error%20code%2020

You have been a very, very naughty boy and not had your machine serviced by a qualified Kubota maintenance centre.

What model number is the tractor

Mode "A" (Test Mode)
1. While holding down both DPF INHIBIT switch and the parked regeneration switch, turn the key switch to "ON" or "START" position.
2. Mode selection display is indicated on the LCD.
3. Press the parked regeneration switch and the mode indicated on the LCD is changed.
4. If "A" is indicated on the LCD, press the parked regeneration switch for more than 2 seconds.
5. Test mode is selected.
6. If parked regeneration switch is pressed, the display item is changed.
7. Turn off the key switch to finish test mode.

Mode "b" (Error Information Clear Mode)
1. While holding down both DPF INHIBT switch and parked regeneration switch, turn key switch "ON" or "START" position.
2. Mode selection display is indicated on the LCD.
3. Press the parked regeneration switch and the mode indication on the LCD is changed.
4. If "b" is indicated on the LCD, press the parked regeneration switch for more than 2 seconds.
5. Error information Clear mode is selected and the expression "PUSH" is displayed.
6. Press the parked regeneration switch for more than 2 seconds.
7. The expression "OFF" is displayed.
8. Turn off the key switch.
Be sure to clear error information by performing this procedure after servicing is finished.

It was made between 1983 and 1990
Kubota B8200 Power:
Engine (gross): 19 hp [14.2 kW]
PTO (claimed): 16 hp [11.9 kW] (gear)
14.5 hp [10.8 kW] (hydro)
You can find more breathtaking information about this tractor at

http://www.tractordata.com/farm-tractors/001/2/7/1274-kubota-b8200.html

you c an find that info on the kubota website