How to identify faults in your metal detector

There are often cases when the new detectorist has to deal with inadequate performance of their metal detector in the field / on location, in the middle of detecting. Often they are sure exactly what they are hearing and may not have a spare detector on hand to help.

The most frequent scenario is when the detector starts giving out tonnes of fake signals without any obvious reasons. No detectorist, wants to stop, collect their things and rush home, or to the store, to check out what is the problem.

Here are some tips to help you to handle the problem on your own!!


Problem 1: Fake Signals

One of the most widespread issues is untypical or fake signals. Here is what one should do:

  • Check the battery, whether it is charged and working properly, because fake signals are frequent when the battery is almost dead. It is always a good idea to have an additional set of batteries when you go to any location.
  • Check whether there are power lines around the patch you are combing through. Radio interference, or other metal detectors close to you can also cause fake signals. To handle this issue, use frequency shift, if such function is present on your detector. If not, you should probably try another location, or further away from your detecting partner.
  • Check powerful gadgets in your pockets or even in the backpack. Modern devices are powerful sources of signals, and sensitive detectors can react to them, as well. Everyone knows not to wear steel-capped boots.
  • If you have checked the above, then the reason must be the machine itself.

If the problem lies in the metal detector itself, you have to find out whether it is the coil or the control unit. To check that, swap over with a compatible coil, yours or another detectorist’s. If the coil functions well, then your coil has a fault. That is why it is always a great idea to bring 2 coils.

If the another coil fails too, then it means the problem is in the control unit. In this case, you definitely need expert advice. You won’t be able to fix the control unit on your own.

Problem 2: Search Coil

Now, the majority of problems that cause faults in the coil can be fixed on your own directly in the field.

  • If the weather is hot, the transmitter gets hot as well, and the loop starts giving you phantom signals
  • If you work in wet weather, or the location has wet grass etc., the same effect can be caused by water getting into the coil
  • If you use coil cover, keep in mind that sand, dirt, or water can still get underneath, preventing the coil from proper performance. You may need to take the cover off and clean it.
  • Sometimes the problem is not in the coil itself, but in the cable. Try to move it back and forth, and if performance of the coil improves, then the cause is in the jack plug.

Read our article: The Confusion Over Coils

Problems That Can’t Be Solved In the Field

Yet, not all issues can be solved directly in the field. There are issues that require an expert’s advice, and servicing / maintenance:

  • Failed mounting in the coil due to physical damage
  • Malaxation caused by heat
  • Damaged loop on your detector

If the issue with metal detector is not fake, or untypical signals, and you experience loss of depth, or inability of the machine to recognize certain metals, maybe the damage is serious, and you should take your detector in to your local store to be repaired.


We hope we have helped you save some grief, or lost time, when detecting out in the field!

One of the best batteries for the metal detector are Nickel-Metal Hydride Batteries (NI-MN). Their capacity is 2-3 times higher as compared with Nickel-Cadmium, but they also can lose their capacity due to difficult weather conditions, such as low temperature. Thus, it is better to choose a powerful battery with the capacity of more than 2000-2500mAH for a long-term metal detecting.