A malfunctioning car key could be caused by the key itself or the car’s radio system. Of course, the key blade itself could also be physically damaged.
Grays Locksmiths work with cars of all makes and models. We can replace damaged, lost or stolen car keys and reprogramme them to match your vehicle. It’ll cost far less than going to a dealership, too.
This article will explain how your car key works and what causes it to go wrong. We hope you find it informative.
How does your car key work?
Before we explain the problems, we’ll explain how your car key works. This will help you grasp the principles behind why your car key malfunctions.
Cars are constantly emitting a radio signal. This is powered by the car battery (even when the car is switched off) and controlled by a part of the vehicle’s ECU (its ‘brain’).
Your key fob also contains a small button battery. Pressing the button means the car’s system and the key share and compare information. If the information matches, the car completes the command from the key (for example, opening/locking all the doors or the boot). It also disables the immobiliser and steering lock when you bring your key into the ignition.
All manufacturers design systems slightly differently for security reasons.
Using the old-fashioned manual key in the door to access your vehicle works just the same as any other lock. However, if the key and car batteries are both functioning, the manual key will activate the central locking. Thus, you can often open all the doors from one manual lock.
If your car battery is disconnected, the central locking won’t work. That’s because there’s no radio signal transmitting from the vehicle. You can still get into your car using the manual key, but it won’t activate the central locking or alarm.
Problems with the car key fob
For the vast majority of modern cars, you’ll use the fob to access your vehicle. Pressing the button on your ‘key’ controls the central locking, using a radio signal to open the door(s).
The most common car key malfunction (by far) is a discharged (‘dead’) key battery. You should expect to need to replace these every few years. Without a battery in the key, the car can’t register it. Therefore, the buttons on the fob are effectively useless.
In most cases, the key starts playing up as the battery drains. You’ll notice problems long before it fully discharges. This usually appears as the central locking only working intermittently or not at all. You might also find that the car alarm plays up after getting in the car.
Get a new key battery from any good auto locksmith.
The other thing to watch out for is physical damage. The fob contains buttons. If the contacts are damaged, or other parts wear out, pressing the button won’t complete the circuit. You’ll need a locksmith to take your key apart and replace or clean the affected parts.
Problems with the manual car key or locks
You could experience problems with your manual access key. These are the same problems you’ll face with any other key, such as those used in your home.
All cars come with manual access keys. In most modern vehicles, these are hidden. You can pull them out of your fob. You usually also need to remove part of the door handle to find the lock.
For example, any of the following (and more) could happen:
- The key blade wears down
- The key blade snaps
- Locks become worn and break
- Dirt and debris fill the locking mechanism
- You could accidentally be using the wrong key
In most cases, you’ll simply need a new car key. However, it’s vital to get this done as soon as possible. The blade could get stuck in the ignition cylinder (where you turn your car on). This is a much more complex and expensive thing to fix.
Problems with the car
The last thing that could impact your car key and make it malfunction is the car battery or control module (ECU).
As mentioned earlier, a completely discharged car battery stops the central locking from working. It’ll also impact the alarm system. The biggest sign of a discharged battery? Your car won’t start, or it’ll really struggle.
The radio signal and codes are controlled and examined by the Body Control Module, part of the ECU. Occasionally, you might find that this develops a fault – for example, condensation might get in after a bad DIY job. This could impact the central locking.
You’ll most likely find that the problems are intermittent and seemingly random. The BCM also controls many other features, such as the alarm, immobiliser, lights and windscreen wipers. If these activate at strange times, there’s a deeper electronic issue.
You’ll need to head straight to an automotive locksmith or electrician for an in-depth diagnosis. Unfortunately, ECU module replacements are often expensive.
What should you do if your car key malfunctions?
If your car key fob stops working, you should first replace the key battery. At most local locksmiths, this only comes to £15 or so, including fitting.
If that doesn’t work, a more detailed look is needed. Take your car to a specialist to find and fix the problem.
At Grays Locksmiths, our auto section is dedicated to replacing and re-coding car keys. If you need help with a malfunctioning car key, please don’t hesitate to contact us. We’ll explain what’s wrong with your vehicle, so you know exactly what to expect.
For a commitment-free and friendly chat, use the contact form below to get in touch.