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If the lock symbol on your dashboard is blinking and your car won’t start, this could be an indication of an issue with your key fob, immobilizer system, or the security settings.
Here’s a detailed guide to help you address the issue step by step.
What Is the Lock Symbol and Why Is It Blinking
The lock symbol that blinks on your dashboard is part of your car's security system. Most modern cars use a transponder key or key fob with a chip inside it that communicates with the car's computer.
When the car detects that the correct key is being used, it lets the car start. But if something goes wrong with that communication, the lock symbol starts blinking as a warning.
This is usually the car’s way of telling you there’s a problem with the key or the immobilizer system, which prevents your car from starting unless the right key is used.
If the lock symbol keeps blinking and you can’t start the car, it likely means the car’s security system isn’t able to recognize the key.
This could be caused by a variety of things, like a problem with the key fob, immobilizer system, or even the key itself.
Related Reading: Car With Lock Symbol Light | How to Fix and Reset Immobilizer System Warning Light
Common Causes of the Blinking Lock Symbol
Key Fob Battery Is Low or Dead
One of the most common reasons the lock symbol blinks is because the key fob has a low or dead battery. When the battery in your key fob starts running low, it may not have enough power to communicate properly with the car’s security system.
As a result, the car might not recognize the key, and the lock symbol will start blinking. Most key fobs take a small coin cell battery that you can easily buy and replace yourself.
Key Is Not Recognized
The lock symbol could be blinking is because the car isn’t recognizing the key you're using.
This could happen if you’re using a spare key that hasn’t been properly programmed, or if you’re using an aftermarket key that doesn’t match the car’s system.
Even a perfectly good key can have trouble communicating with the car’s immobilizer system if it’s been damaged or the transponder chip inside the key is faulty. Trying to use another key that you know works. If the car starts without any issues, then the problem is likely with the key you were using before.
Immobilizer System Is Malfunctioning
The immobilizer system is a security feature that prevents the engine from starting unless the car recognizes the correct key. If there’s a malfunction in the immobilizer system, the lock symbol may blink, and your car won’t start.
There’s an issue with the car’s computer system or a problem with the wiring in the security system. It’s usually best to take your car to a mechanic or dealership for diagnosis and repair.
They will be able to check if there’s a problem with the immobilizer system itself, or if the issue is related to other parts of the car’s security system. Of course, you could also use your car diagnostic scanner to check things out yourself first. If you have a scanner, it might show you some error codes that can point you in the right direction.
This can sometimes help you identify small issues that you can fix on your own, saving you a trip to the shop.
Security System Settings or Mode
The blinking lock symbol can be caused by the car’s security system settings being changed, or the system being in a certain mode.
For example, some cars have a learning mode or special settings that can make the lock symbol blink when they’re activated.
This can happen if you’ve recently had your car serviced, or if someone accidentally changed the settings on the security system.
Wiring or Connection Issues
If there’s a loose connection, damaged wire, or corrosion somewhere in the system, it can cause the car to not recognize the key properly, and the lock symbol will blink as a warning. This is less common.
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What to Do if Your Car Won’t Start and the Lock Symbol Is Blinking
Check the Key Fob Battery
The most common cause of a blinking lock symbol is a low or dead key fob battery.
A weak battery may prevent the key fob from communicating properly with your car’s security system, causing the car not to start.
Most key fobs use a CR2032 coin-cell battery, which can be easily purchased from most stores. After replacing the battery, try using the key fob again to see if the lock symbol stops blinking and the car starts.
Try Using a Spare Key
Using a spare key can help you determine if the problem lies with the original key or key fob. If the spare key works and the car starts, then the issue is likely with the original key or key fob. In this case, you may need to reprogram or replace the faulty key. If the spare key doesn’t work either, the issue may be with the car’s security system itself, rather than the key.
Reprogram the Key Fob
In situations where the key fob is not being recognized by the car or the immobilizer system is malfunctioning, reprogramming the key fob can often solve the issue.
Reprogramming is necessary if the car’s security system and the key fob become desynchronized. This can happen if you’ve recently replaced the battery in the fob or if the fob has experienced some other form of malfunction.
Reset the Security System
If the key fob and the car seem to be in sync, but the car still won’t start and the lock symbol continues to blink, the problem might lie with the car’s security system.
To reset the system, you will generally need to turn the key to the ON position (without starting the engine) and leave it there for about 10-15 minutes. This will allow the system to reset itself.
Can I Program Key Fob Myself
Yes, you can definitely program your key fob yourself, and it’s actually pretty straightforward with the right tools. One of the best tools for the job is the Ancel V6 Pro.
Plug the OBD scanner V6 Pro into your car’s OBD port. This port is typically located under the dashboard on the driver’s side, near the steering wheel. Once the scanner is plugged in, turn the car’s ignition to the "on" position (just the second click, not starting the engine). You’ll know it’s on when all the dashboard lights come on, but the engine isn't running.
Turn on your OBD2 scanner V6 Pro. You’ll see the scanner’s main menu on its display screen. From here, navigate through the options using the arrow buttons. Look for a menu option that says “Key Fob Programming” or “Remote Key Programming.” Select that option, and the scanner will connect to your car's computer system.
Select Key Type: The scan tool will ask you to choose the type of key fob you're programming. This is typically a simple choice between "Standard" or "Transponder" key fob, depending on your car’s system. Choose the correct option and hit Enter.
Press the Button on Your Key Fob: The scan tool will prompt you to press a button on your key fob, usually the Lock button, to sync it with the car. Press the button and hold it down for a few seconds until the scanner acknowledges the input. The scanner may show a message like “Key fob detected” or something similar.
Wait for Synchronization: After pressing the button, the scanner will send a signal to your car’s security system, telling it to register the new key fob. You may see a message on the scanner that says “Programming in progress” or “Synchronizing key fob.” This process can take a few seconds.
Confirmation: Once the key fob is successfully programmed, the auto scan tool will display a success message like “Key fob successfully programmed.” At this point, your new key fob should now be linked to your car’s system. Some scanners may also prompt you to press the Lock and Unlock buttons on the fob again to finalize the connection.
Test the Key Fob: The scanner might give you a final prompt asking you to test the key fob by locking and unlocking the car’s doors. Do this to make sure the fob is working as expected.
FAQs
Can a dead key fob battery cause the lock symbol to blink?
Yes, a dead or low key fob battery can prevent the car from recognizing the key and cause the lock symbol to blink.
What should I do if my car won’t start and the lock symbol is blinking?
Try using a different key, replacing the battery in the key fob, or resetting the security system. If none of these work, contact a mechanic or dealership for help.
How can I prevent the lock symbol from blinking in the future?
Regularly replace the battery in your key fob, keep spare keys in good condition, and have your car’s security system checked periodically to avoid issues.
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