Sonar Connection Lost
Raymarine Chartplotter
Severity: ModerateWhat it means
Raymarine 'Sonar Connection Lost' (or 'No sonar found' / 'Transducer not connected') means the plotter's fishfinder side can't reach the sonar — either the internal sounder isn't seeing its transducer, or an external black-box module (RVX1000, CP470, CP570) has dropped off the network.
The chart and GPS keep working; you just lose the sounder picture until the connection is restored.
Affected Models
- Raymarine Axiom RV / Axiom Pro RVX (built-in RealVision sonar)
- Raymarine Axiom 2 Pro with RVX1000 module
- Raymarine eS / gS Series with a CP-series black-box sonar
- Systems using a CPT, RV, or B-series / Airmar transducer
Common Causes
- Transducer cable loose or unlatched at the back of the plotter or sonar module
- Black-box sonar module (RVX1000, CP470/570) lost power on its own circuit
- Module dropped off the SeaTalkHS / Ethernet network — switch or cable fault
- Transducer extension cable connector corroded (the join is a common failure point)
- Transducer element failed (water ingress)
- Sonar firmware out of step with the plotter after a partial update
How to Fix It
-
Identify your sonar setup.
Built-in sonar (Axiom RV/RVX): the transducer plugs straight into the plotter — check that cable.
Black-box sonar (RVX1000, CP470/570): there's a separate module somewhere on the boat — check its power and its network link first, then its transducer cable. -
Reseat the transducer cable.
At the plotter or the sonar module, unplug the transducer cable and push it firmly back in until the locking collar seats.
If there's an extension cable join, open it, check for corrosion or water in the connector, clean it, and reconnect.
That join is the single most common cause of intermittent sonar loss. -
Check the black-box module.
If you run an RVX1000 or CP-series module, find it and check its power LED.
No power means a tripped breaker on its circuit.
Then check its Ethernet / SeaTalkHS cable to the network switch or the plotter — reseat both ends.
A module that's powered but not on the network won't show up as a sonar source. -
Check firmware versions.
After a software update, the plotter and a black-box sonar module need compatible firmware.
Use Raymarine's LightHouse update process to bring everything to the same release.
A mismatch can leave the module visible on the network but refusing to hand over a sonar feed. -
Test for a dead transducer.
If the cable, module, and network all check out and sonar still won't connect, the transducer element may have failed — water gets into older transducers and kills them.
The giveaway is a transducer that the module simply won't acknowledge no matter what.
Replacement transducer; have a dealer match it to your sonar module.