Bobcat D3905 (39-05) Fault Code: Left CAN Joystick X-axis Not in Neutral
Also shown on the panel as 39-05 · Also called Left CAN Joystick X Axis Not in Neutral, Left Joystick X-Axis Not in Neutral
Left CAN Joystick X-axis Not in Neutral · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
D3905 (panel code 39-05) sets when the drive/drive plus controller sees the left joystick X-axis out of neutral while press to operate loader (PTOL) is engaged and the engine is running, in ISO mode. Drive functions are disabled until the joystick is confirmed neutral and the fault clears.
High severity. Drive functions are disabled while this code is active, which stops the machine from being driven until the joystick is verified neutral and the cause is fixed. It is not an engine or structural damage risk, but it takes the machine out of service.
What does Bobcat error code D3905 mean?
Code D3905 means the drive/drive plus controller has detected that the left joystick's X-axis is not centered in neutral at a moment when it needs to be: PTOL is engaged and the engine is running. This check only happens in ISO mode. Because the controller cannot confirm the joystick is neutral, it disables drive functions as a safety precaution so the machine does not lurch or move unexpectedly.
This is a positional/logic fault tied to the joystick's neutral sensing, not necessarily a wiring failure on its own. It can be caused by something as simple as a boot pushing the stick off-center, or as involved as a bad connector or controller.
What triggers a Bobcat D3905 code?
The code sets when all of these are true: key switch/(run/enter) is on, ISO mode is selected (on SJC machines), the engine is running, and PTOL is enabled while the left joystick X-axis is reporting out of neutral.
Common causes of D3905
- Rubber boot or the operator physically holding the left joystick out of neutral
- Left joystick base fault
- Drive/Drive Plus controller fault
- Moisture, corrosion, or pushed-back pins in the left joystick assembly or AWS/SJC harness connectors
- Intermittent fault where the root cause may not be found if the code is not active at the time of testing, possibly from loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these
How to troubleshoot Bobcat D3905: first checks
- Confirm the left joystick is physically free to return to neutral and is not being held or obstructed by the operator or the seat/armrest position.
- Check the rubber boot around the joystick base. Make sure the part number marking on the inside of the boot faces the front of the machine, since incorrect orientation can bind the stick off-center.
- Inspect the left joystick assembly and AWS/SJC harness connectors for moisture, corrosion, or pushed-back pins.
- If operating with remote control, use the diagnostic software's Diagnostics > Radio Remote Control Diagnostics menu to verify the left joystick is reporting correctly.
- If the code is intermittent and not currently active, check all connections in the circuit anyway since the cause may not show up unless the fault is present at the time of testing.
- If the joystick base and wiring check out, suspect the drive/drive plus controller.
How the code clears
The condition for clearing D3905 is PTOL enabled. No separate reset procedure is listed for this code; once the left joystick is confirmed in neutral and the underlying cause is corrected, cycling PTOL should allow the code to clear.
Affected models and serial ranges
D3905 appears in our records across 16 Bobcat models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| S510 | SN A3NJ11001-99999, SN A3NK11001-99999, SN ATZC11001-ATZC99999 |
| S530 | SN A7TV11001-99999, SN ATZD11001-99999 |
| S550 | SN A3NK11001-A3NL99999, SN A3NM11001-99999 |
| S570 | SN A7U711001-799999, SN A7U811001-899999 |
| S590 | SN ANMN11001-99999, SN ANMP11001-99999 |
| S630 | SN A3NT12370-99999, SN A3NU11001-11111, SN A3NU11112-99999 |
| S650 | SN A3NV11001-13098, SN A3NV13099-99999, SN A3NW11001-11248 |
| S750 | SN A3P211001-299999 |
| S770 | SN A39511001-99999, SN A3P411001-99999 |
| T550 | SN A7UJ11001-AJZV12276 |
| T590 | SN ALJU11001-999999, SN B37811001-999999, SN B3Z711001-999999 |
| T630 | SN A7PU11001-11663, SN A7PU11664-99999 |
| T650 | SN A3P012214-099999, SN A3P111242-199999 |
| T750 | SN ANKA11001-A99999 |
| T770 | SN A3P811001-899999, SN A3P911001-999999 |
| T870 | SN A3PG11001-99999, SN A3PH11001-99999 |
Frequently asked questions
What does D3905 mean on a Bobcat machine?
It means the drive/drive plus controller detected the left joystick's X-axis was not in neutral while press to operate loader (PTOL) was engaged and the engine was running, in ISO mode. The controller disables drive functions until this clears.
Why does D3905 only happen in ISO mode?
The neutral check tied to this code is specific to ISO mode joystick control. It is not monitored the same way outside of ISO mode.
Can a misaligned rubber boot cause D3905?
Yes. The rubber boot around the left joystick base can hold the stick out of neutral if it is not oriented correctly. The part number on the inside of the boot must face the front of the machine.
Will D3905 clear itself?
The listed condition for clearing the code is simply PTOL enabled, once the joystick is confirmed neutral and any underlying fault (wiring, boot, controller) is corrected. No separate reset procedure is listed.
What should I check first if my Bobcat throws D3905?
Check that nothing is physically holding the left joystick out of neutral, inspect the rubber boot orientation, and look at the joystick assembly and harness connectors for corrosion or pushed-back pins.
Does D3905 happen with radio remote control?
It can. If the machine is being run with remote control and D3905 sets, use the diagnostic software's Radio Remote Control Diagnostics menu to verify the left joystick is operating correctly.
Is D3905 an intermittent fault sometimes?
Yes. If the code is not active at the time of testing, the root cause may not be found immediately. Loose connections, corrosion, pushed-back pins, the controller, or the wire harness are all possible contributors.