How to Tell if Transducer is Bad: Troubleshooting Symptoms (2024)

Featured Image - CO-0213 - how to tell if transducer is bad
Featured Image – CO-0213 – how to tell if transducer is bad

Owning a fish finder is a wonderful thing as most of the time it’ll be working properly and you’ll be able to see all sorts of things underwater like the depth, structures, and fish that make fishing a lot easier and help you catch more.

Join me as we take a look at how to tell if a transducer is bad and how you can troubleshoot and fix your fish finder at home without calling in the pros.

Transducers Issues

Part of owning a fish finder is also managing the times when they don’t work properly.

I have had days out of the water then I’m in 1000 feet of water and I’m seeing incorrect depth readings of 30 feet, or I’m only seeing a surface reading on my display.

I used to panic in these moments thinking that my depth sounder that I invested in and rely on was broken, but most of the time it’s actually a simple fix on either the transducer or the transducer cable.

How to troubleshoot your fish finder transducer

Before we dive into the details of how to fix your fish finder transducer we first need to understand how to be sure that the issue you’re seeing is a transducer performance issue and nothing else.

Fish finders are made up of two main parts, the display unit and the transducer unit which are connected via cables to each other and to a power source, usually a marine battery like the ones in my best trolling motor battery review.

Transducer Unit

If the main unit, which is the display, isn’t turning on or you’re seeing a weak signal then chances are the main issue lies with the main unit (display) and not your transducer so check your battery and the connections to see if the signal returns, if not get the user manual out and contact company support.

Display Unit

If your display unit is powered on with a strong signal then it’s your fish finder transducer that needs looking at and here is how to tell if a transducer is bad.

What are the signs that I have a bad transducer?

Lowrance Transducer Display
Lowrance Transducer Display

The main indicators that your fish finder transducer needs some love and attention include:

Your display shows an incorrect depth reading meaning it’s showing say 50 feet when you know you’re in 100 feet plus

  • Your display shows a surface reading but no bottom depth reading, meaning your transducer is only sending out pulses of its sonar sound waves or receiving part of the sonar waves on its sensors
  • Your display shows erratic depth readings jumping from one depth to another, especially when your boat is moving from slow speeds to a higher speed

If you are experiencing any of these performance issues on your boat then you need to work out what is causing the transducer issues.

What causes a transducer to go bad?

There are quite a few different things that can affect your transducer’s performance, even if it’s in good condition.

Understanding them will help you either fix the transducer performance issues quickly on the water or let you know if you need to call a professional out or buy a new transducer.

Was the transducer installed correctly?

Transducer Installation
Transducer Installation

If your fish finder is new and you already have an issue with your depth readings then chances are it was a bad transducer mounting or installation and you should take a look at the installation manual and check if it was done correctly.

Is the transducer face pointing in the right direction?

To get an accurate depth reading your transducer needs to be mounted and positioned correctly on your boat and most transducers should be facing straight down and be perpendicular to the water.

This allows the narrow beam of sound pulses or sonar pulses created by electrical energy (the clicking sounds you can sometimes hear) to go straight down and get good readings.

When transducers don’t point straight down the beam is sent out at an odd angle which causes the depth readings to be distorted and inaccurate.

Is the transducer covered with any marine growth?

Marine growth such as barnacles and algae can block the signals from being sent out of or received by transducers which will give you faulty depth finder readings.

This happens because perhaps only the same frequency signal can be sent and/or received resulting in a surface depth reading only or sometimes no reading at all.

Are the connector cables connecting everything still ok?

Life on a boat is tough and the connector cables connecting your main unit to the transducer and to the power source can suffer from corrosion, even in the fuse holder and switches.

If there is a damaged connection, no information can be transferred from the main unit to the transducer and thus the whole system breaks.

If you do see signs of corrosion or damage on the cables, switch or fuse box, then chances are it’s a cable issue.

Is cavitation affecting the transducer?

Air Bubbles
Air Bubbles

Cavitation is water turbulence in the form of air bubbles that comes off your boat, engines, or trolling motor, and when you ask the question why won’t my transducer work? This is often the reason as it’s quite a hard one to check.

Air bubbles

When there are too many air bubbles around your transducer, the transducer can not send out or receive the appropriate sonar signals as the sonar signals are hitting air instead of water and therefore can not travel to the bottom of the lake/sea/river.

If this is happening, it means your transducer is mounted on the wrong part of your boat with regards to the wash of the engines and might need moving.

Is your transducer experiencing interference from another depth sounder nearby?

If multiple depth sounders (fish finders) are working at the same time on the same boat they will both experience the same problem. One machine will cause signal interference with the other machine causing both of the fish finders/depth sounders to give incorrect readings.

This will only happen if you have two transducers on one boat or if you are very close to another boat using a depth sounder.

Are there signs of damage on your transducer?

Depth sounders are quite delicate things and since your transducer is on the hull of your boat it’s very easy to accidentally damage it by clipping some debris or by it getting petroleum residue on the outside and then suffering corrosion.

You could damage your hull with a coconut while driving your boat around, something I have done.

After a huge tide washed all the coconuts into the harbor, driving to avoid them was like dodging landmines. I did quite well but one clipped my transducer and I had to jump in and realign it, thank god it wasn’t damaged.

Transducers work by sending out sonar from the piezoelectric element inside them. The piezoelectric element on transducers is made from piezoelectric crystals and if the structure of the piezoelectric crystals is affected then the electrical pulses are not sent out correctly.

Fixing Your Depth Sounder Transducer

Fish Finder on a Table
Fish Finder on a Table

Now we know what to look for to see if you have a bad transducer, let’s discuss what you can to try and fix it at home.

Poor installation, transducer placement, cavitation, and cable checks

If you think the issue is to do with the depth sounder installation, transducer placement, or cavitation then you can solve the issues with these steps.

  • Check all the cables are connected properly and the transducer switch and reconnect as needed
  • If you find a corrode cable or a damaged cable, replace it and test to see if it was the problem causing your transducer to malfunction
  • Look at your transducers angle to the water and adjust it to be parallel to the water level
  • If it’s a cavitation issue, make sure the transducer is on the starboard side if you have a single-engine and if you have two engines make sure it’s in the middle of the two engines but as low down on the hull as possible – if not you’ll need to move it

Cleaning Your Transducer

If you see that your transducer is in good condition but just needs a clean then grab a soft cloth and some mild detergent and begin cleaning your transducer but avoid scratching it.

It’s best to do this out of the water having disconnected your transducer and removed it from your boat.

Once you have cleaned your transducer, you can then paint it with antifouling paint which will stop anything growing on it.


Make sure you use a water-based solvent antifouling so it doesn’t damage the surface of your transducer.

Interference From Another Depth Sounder

If you have two transducers on your boat and you think interference is the issue, check by disconnecting one and testing the other and vice versa.

If interference is the problem, then reinstall one of your transducers further away from the other and consult the factory settings to make sure they are far enough apart.

Here’s an informative video about fish finder interference problems…

Fix Fish Finder Shutting Down? Interference Issues? (EASY FIX)

Dealing with a damaged transducer

If you find that your transducer is damaged then the likelihood is you’re going to need a pro to take a look at it and assess the damage, and chances are you will probably need a new one.

How do you check a transducer to see if it is good? (Testing)

Once you have attempted to fix your transducer it’s time to do some testing. You should do your test on the water in a depth that you know so you can see if the reading it gives is correct or not. 

First, drive your boat to a depth you know, stop your vessel and turn on your fish finder and wait. If you get a solid reading and it’s showing the right depth then you know it works while your vessel is stationary.

Now try moving at speed to test if it works while you are moving. Starting slowly at 2-3 knots and slowly going faster and faster to around 10 knots. Keep an eye on the display to see if it still works. If so, your test is complete and the transducer is fixed.


Do transducers wear out?

Yes transducers wear out. The element inside them is made from crystals, as I mentioned earlier, and through wear, tear and overheating, these crystals can crack and cause transducers to degrade and eventually fail altogether.

Will a transducer work out of the water?

A transducer will not work out of the water as it can not send or receive sonar waves through the air and therefore it has to be submerged to work.

Does it hurt a transducer to run out of water?

Running transducers out of the water can cause them to break as when out of the water the element inside overheats and causes the crystals to crack and thus damages the unit.

Can you test a transducer out of the water?

You can not test a transducer out of the water as it won’t be able to read anything since it can not send out or receive sonar waves through the air, it must be submerged to be properly tested.

That being said, you can do a test to see if it is generally functioning which we will look at next.

How do you test a transducer at home?

Testing transducers at home is possible if you have a pressure transducer but it requires some tools and you need to be careful the pressure transducer doesn’t overheat or it might get damaged. Here is some information on how to do it.

You won’t be able to test if it reads depths properly at home, only if it works and powers on, as it needs to be in a lake, river, or the sea to give you depth readings.

Sounding Out

Thanks very much for reading my article on how to tell if transducer is bad. I hope you enjoyed it and have now learned everything you need to work out if it’s your transducer that isn’t working, why, and how to fix it at home if it’s possible.

Knowing how to fix the simple things yourself can save you a boatload of cash so it’s worth knowing as much as you can about it . 

Please share this article with all your boating buddies as they need this kind of info too and check out some of my other articles about the best fish finders on the market.

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