Ostranauts transponder
What it does, what 'ant fault' means, and when to switch it off.
Your ship's ID beacon.
A transponder broadcasts identification; the antenna transmits it.
Stations and other ships read your transponder to know who you are. It only works if the ship has an operational XPDR antenna: the two components are separate.
The flashing warning explained.
You have a transponder but no working antenna.
When the ship flashes ant fault, either the antenna is missing, damaged, or disconnected. Flying through the ship graveyard risks collisions with junk that damage exterior components: check the antenna first, then the hull around it.
Detection is a choice.
Players toggle the transponder to avoid attention or fines.
While docked or operating quietly, switching the transponder off hides your identity: useful in smuggling-adjacent play. The common mistake is forgetting to switch it back on before undocking, which leaves you transmitting nothing and triggers the ant fault warning.
Common questions
What does the transponder do?
It identifies your ship to stations and other vessels. Without a working transponder and antenna, you cannot transmit: which shows up as the flashing 'ant fault' warning.
What is 'ant fault'?
Antenna fault: you have a transponder but no operational antenna. The antenna can be missing or damaged: collisions with junk in the ship graveyard are a common cause.
Should I turn the transponder off when docked?
Players turn it off to avoid detection or fines in sensitive situations. Remember to switch it back on before undocking or stations may treat you as unidentified.
Why does my transponder break when I uninstall it?
Community reports say uninstalling a transponder often breaks it. Cut power first, and expect to repair or replace it after removal.
How do I fix a damaged antenna?
Repair the XPDR antenna like any exterior component, then confirm the ship has no active hull breaches around it. If the warning persists, uninstall and reinstall the antenna.