11 - Serial communication error.
An official Fujitsu General error table labels code 11 as a serial communication error, indicating the system is not communicating normally across the control path.
Family context is taken from Fujitsu General's floor-mounted split-system product pages. Error-code mappings below are conservatively taken from an official Fujitsu General installation-manual error table for a floor-mounted indoor unit, so exact display behavior and applicability can vary by controller and connected system type.
Severity
High
Display
On supported floor-mounted systems, the official installation manual says the indoor unit shows errors by lamp blinking patterns during operation; some Fujitsu General remotes also have a service-check mode that can show a 2-digit code.
Support first?
Often not
Models in range
AGU9RLF, AGU12RLF, AGU15RLF
What to do first
Start with these checks
- 1Turn the system off, wait briefly, and restore power once
- 2Note the exact code or lamp pattern before the display clears
- 3Avoid repeated restart attempts if the code returns immediately
Likely causes
What usually sits behind this code
Communication fault between connected control boards or units
Wiring or connector issue affecting the control signal
A control PCB fault interrupting normal serial communication
Contact support
Contact customer support if any of these apply
- !The code returns after a single restart
- !The indoor or outdoor unit will not operate normally
- !You also see additional communication-related faults
- - The official installation-manual snippet maps code 11 to Serial communication error.
- - Fujitsu General's support-tool pages also state their technician app contains current-model error messages.
Related codes
Nearby codes in this family
Source notes
Source and scope
Source: Fujitsu General installation manual
Official error-code table snippet for a Fujitsu General floor-mounted indoor unit lists code 11 as Serial communication error.
Last reviewed: 2026-04-19
Use this as an official-first pointer, not a repair authorization. Exact troubleshooting steps and code visibility vary by model, controller, and system configuration.