Buttons on a car key are linked in with the circuit board inside the key. This is then powered by a battery.

If your car key buttons aren’t working, there is a very high chance that the battery in your key is dead. This means the battery will need replacing. There is generally no need for an auto locksmith in situations like this as it can quite easily be done yourself. Most car keys do have access to the battery and it is simply a case of removing it and inserting a new one.

Whilst this is the case for a lot of car keys, some aren’t this easy. For example, some BMW keys have their battery soldered onto the circuit board inside the key and it is designed to recharge whilst it is in the ignition. If there is a fault with a battery like this, to replace it you’ll need to de-solder the old one and solder on the new one. BOTR offer this service if this is something you’re interested in!

Another reason for no communication between your key fob and door locks could be due to a faulty door lock actuator. Very often if this is the case, either the motor inside the actuator needs replacing or you’ll need a new actuator.

Other reasons for your buttons not working include water corrosion. If your key has gotten particularly wet, the circuit board inside can get damaged and therefore signals can’t be transmitted to the buttons rendering them unresponsive. Another reason for button failure is general wear and tear. After thousands of ‘presses’, buttons can simply break and therefore become unresponsive. Cold weather can even cause a battery to be unresponsive if it is particularly old.

A bit of rain water tends to be no issue whatsoever, but sending your keys for a spin in the washing machine is a big cause of water damage in car keys. A lot of people find out they’ve done this and straight away go to check if it still works, but this is the worst thing you can do.

A key is made up of a transponder, and a circuit board (powered by the battery). Your buttons are connected to the circuit board, so when you press them you’re just pushing water deeper into the circuit board. Never try to start the engine either.

The best thing you can do if you’re in this situation is to immediately pry open your key. A lot of keys don’t just slot together though, so prying it open will permanently break it – you’ll have to use silicone to put it back together.

After prying the key apart, you MUST take the battery out to prevent any short circuits. Short circuits can fry the circuit board altogether. Next thing is to get isopropyl alcohol and clean the board. Washing machine water is worse than normal water since the detergent leaves behind a conductive residue. 

Once the board is clean, let it dry for at least 48 hours. Most OEM keys have the transponder (the component that communicates with the vehicle’s immobiliser) attached to the circuit board so during this time you’re allowing that to dry out fully too. Once this time frame has elapsed, put the circuit board back in the key shell along with a new battery. If you don’t know what battery you need, read the front of your old one since that will say something like ‘CR2032’, just as an example. Silicone the edge of your key and try to stick it back together.

Whilst this is the process you should follow should you find yourself in this situation, its quite often a temporary fix anyway. You may find the key will work intermittently, maybe you can’t afford to wait 48 hours before using it again, or maybe the key will start falling apart shortly afterwards. If your key has gotten particularly wet, it is often advised to bite the bullet and get a new key programmed. Feel free to get in touch with Back on the Road Auto Locksmith Ltd by clicking here if this is something you’re interested in.

DISCLAIMER: Any procedures described here are undertaken at your own risk. Back on the Road Auto Locksmith Ltd accepts no responsibility for injury or damage resulting from following the above information provided.

If you have a bladed ignition, if the blade goes in and turns the ignition, the blade won’t be the problem. The battery categorically won’t be the problem since these only operate the buttons/central locking. This means the only thing that can be preventing the engine from starting (that is key related), is the transponder. The best way of knowing whether this still works is to get an auto locksmith like Back on the Road Auto Locksmith out to run signal testing on the transponder since this does require a specialised device. It involves running tests on the transponder and ignition coil. If the problem isn’t transponder related, it will very likely be something else, such as an ignition related issue.

If you have a proximity/smart key (no bladed ignition), the key may not start the engine because of a flat battery, a faulty transponder or broken 3D inductor. People always instantly think of the battery as the problem (which it can be), but the 3D inductor is a surprisingly common flaw in proximity keys. To diagnose the issue, first, try replacing your key’s battery. If the problem persists, move onto the 3D inductor. The role of the 3D inductor is for proximity (hands free) functions to work regardless of whether your key is upright, upside down, sideways etc; it acts as an ‘omnidirectional antenna’. If it is broken, the push-button start won’t work unless the key is pushed up against it; put the key up to the stop-start button and try pressing it. If the engine turns on, the 3D inductor is broken and will need replacing if you want ‘hands free’ features back. If the engine doesn’t ignite when you press the start-stop button with the key pushed up to it, the problem won’t be the 3D inductor so could be the transponder, or something deeper rooted within the vehicle.

Regardless of what key you’ve got, if the transponder is at fault, the most efficient solution is to get a new one programmed. Again, this  requires an auto locksmith with specialised tools. If the key isn’t the problem, diagnostic equipment will be needed to run various tests on your vehicle to source the issue.

If you have a Mercedes, your key works differently. It communicates with the immobilizer via an infra-red signal, and sometimes something can block these signals from transmitting efficiently.

Staying on the topic of Mercedes, if your key is turning but engine isn’t starting, very often the problem here lies either in the key or the EIS (Electronic Ignition Switch). It would be advised to call an auto locksmith about this since the solutions can be very complex. If your Mercedes key won’t even turn in the ignition, then this is very often a steering lock failure, which can be an even more complex fix.