MX5400 E-21 error showing in hour meter "CAN Communication Trouble"

w.reiche

New member

Equipment
Kubota MX5400
Nov 21, 2022
5
0
1
Ottawa
MX5400 E-21 error showing in hour meter "CAN Communication Trouble"

Manual say to "Contact your KUBOTA dealer".

What does this error mean? Is it okay to run the tractor with this error showing?
How do I fix this error.

It was -18C out yesterday, with about a foot of snow on the ground. Tractor started okay and I used for about an hour. I shut it off and restarted it about two hours later and the E-21 error code started flashing in hour meter. Everything still works okay.
 

DustyRusty

Well-known member

Equipment
2020 BX23S, BX2822 Snowblower, Curtis Deluxe Cab,
Nov 8, 2015
6,436
5,054
113
North East CT
Less than one minute using Google.
A "E-21" error code on a Kubota machine typically indicates an issue with the engine coolant temperature sensor, meaning the sensor is not sending accurate readings about the engine's temperature, potentially causing the machine to run too hot or too cold depending on the malfunction.

Key points about the E-21 error code:
  • Sensor problem:
    The primary cause is a faulty coolant temperature sensor, which could be damaged, dirty, or improperly connected.

  • Check the sensor:
    To troubleshoot, check the sensor for any visible damage, clean it if necessary, and ensure it is properly plugged into the engine harness.

  • Consult the manual:
    Always refer to your specific Kubota machine's operator manual for the most accurate interpretation of the E-21 code and troubleshooting steps.

What to do if you see the E-21 error code:
  • Shut off the engine: Turn off the machine immediately to prevent potential engine damage.
  • Check the coolant level: Ensure the coolant level is within the recommended range.
  • Inspect the sensor: Visually check the coolant temperature sensor for any damage or loose connections.




  • Contact a Kubota dealer: If the problem persists after checking the sensor, contact a qualified Kubota service technician for further diagnosis and repair.
 
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GreensvilleJay

Well-known member

Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
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113
Greensville,Ontario,Canada
re: "CAN Communication Trouble"
It means that one of the computers can't talk to the other computers. All of them are interconnected with special twisted pair cabling and terminators. For some 'reason' they ain't talking to each other. I don't have Kubota's 'bible' on how CAN works on your machine, the WSM will have a wiring diagram, so you can see how many 'computers' are involved. 'computer' can be the dash, the ECU, some valve, ?? CANbus is very sensitive to physical wiring and connectors. The 'computers' are supposed to run self checks and 'repair' a downed link at regular intervals( that's buried in the CANbus bible.
Since it still runs, the ECU is 'good'. It might just be the 'dash display' isn't 'happy'. Do you still get RPM and other normals on the screen ?
Dang -18C is COLD,so something as silly as cold shrinks plastic, connector backs out a bit, CAN signal is disconnected, error,error ,error....... If you can get to the connector, key off, remove ,reinstall 2-3 times, be sure they 'click -lock'. Hopefully something easy.
Again , don't know your machine and know too much about CAN