Bobcat M4304 (43-04) Fault Code: Keyless Panel No Communication
Also shown on the panel as 43-04
Keyless Panel No Communication · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
M4304, shown on some panels as 43-04, means the gateway controller cannot communicate with the keyless panel over the CAN network. It sets with the key switch (run/enter) on, and it can also appear if a machine was switched from a keyless panel to a standard panel without a proper downgrade procedure.
Medium severity. The machine will typically still run, but without keyless panel communication you may lose keyless entry/start functions and related displays. Treat it as a diagnose-this-shift issue rather than an emergency shutdown, unless it is paired with other drive or safety-related faults.
What does Bobcat error code M4304 mean?
M4304 (panel display 43-04) is set by the gateway controller when it loses CAN communication with the keyless panel. The keyless panel and the gateway controller talk over a CAN bus, and if that link drops, the controller cannot confirm the panel's status or pass its commands, so it logs the fault.
This code can also show up as a side effect of a panel swap: if a machine is changed from a keyless panel back to a standard panel and the software downgrade isn't done correctly, the gateway controller still expects to hear from a keyless panel that is no longer there (or is not properly recognized), so it logs a no-communication fault.
This is fundamentally a wiring and communication fault, not a hydraulic or engine problem. It affects convenience and access features tied to the keyless panel rather than core machine functions, but it should still be run down promptly since it points to a real wiring or controller issue on the CAN bus.
Common causes of M4304
- Panel was switched from a keyless panel to a standard panel without performing the proper downgrade procedure.
- Blown or missing fuse: listed variously as Fuse 6, FRC1 fuse 4, or FRC1 fuse 6 depending on the machine/harness variant.
- CAN communication wire 91xx/95xx shorted to supply voltage, shorted to ground, or open.
- CAN communication wire 92xx/96xx shorted to supply voltage, shorted to ground, or open.
- Switched power wire 1590 open, or ground wire 2250 open.
- Fault in the left hand panel.
- Fault in the keyless panel itself.
- Fault in the gateway controller.
- Moisture, corrosion, or pushed-back pins in the gateway controller connectors, left hand panel connectors, keyless panel connector, mainframe harness, or cab harness.
- Intermittent fault: if the code is not active at the time of testing, the root cause may not be found immediately. Probable causes in that case include loose connections, corrosion, pushed-back pins, the controller, the wire harness, or a combination of these.
How to troubleshoot Bobcat M4304: first checks
- Confirm whether the machine was recently switched from a keyless panel to a standard panel; if so, verify the downgrade procedure was completed correctly.
- Check the relevant fuse for this circuit (Fuse 6, or FRC1 fuse 4/6 depending on your machine's harness variant) for continuity and proper seating.
- With key switch (run/enter) on, inspect CAN communication wires 91xx/95xx and 92xx/96xx for shorts to supply voltage, shorts to ground, or open circuits.
- Check switched power wire 1590 and ground wire 2250 for continuity; both must be intact for the panel to communicate.
- Inspect all related connectors, gateway controller, left hand panel, keyless panel, mainframe harness, and cab harness, for moisture, corrosion, or pushed-back pins.
- If the fault is intermittent and not present during testing, wiggle-test harness connectors and check for loose connections rather than assuming a clean pass means no problem exists.
How the code clears
Once the repair is complete, cycle power (turn the key switch off and back on) to clear the code. No separate clearing step is listed beyond this power cycle.
Affected models and serial ranges
M4304 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, SN A3NW11249-99999 |
| S750 | SN A3P211001-299999 |
| S770 | 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 Bobcat code M4304 mean?
It means the gateway controller cannot communicate with the keyless panel over the CAN bus. It can also trigger after switching from a keyless panel to a standard panel if the downgrade wasn't done properly.
Is M4304 the same as 43-04?
Yes. 43-04 is the numeric panel display form of the same fault, M4304.
Can I still drive or operate the machine with M4304 active?
The code is tied to keyless panel communication rather than core drive or hydraulic systems, but any CAN communication fault should be diagnosed promptly since it points to a wiring or controller issue that could affect other systems sharing that harness.
I just swapped from a keyless panel to a standard panel and now I have this code. Why?
If the panel swap wasn't followed by the proper downgrade procedure, the gateway controller still expects communication from the keyless panel and logs M4304 as a no-communication fault.
Which fuse should I check for M4304?
Depending on your machine and harness variant, check Fuse 6 or FRC1 fuse 4/6. Confirm it is not blown and is seated properly.
How do I clear M4304 after fixing the problem?
Cycle power by turning the key switch off and back on. No other clearing procedure is listed.
Why does this code come and go?
Intermittent CAN faults are often caused by loose connections, corrosion, or pushed-back pins in the connectors rather than a fully failed component. If the code isn't active during testing, a wiggle test on the harness and connectors is a good next step.