Key Not Detected Mercedes : Explained
The message Key not detected Mercedes or Mercedes key not recognized is a common issue that can occur with modern Mercedes-Benz vehicles, particularly those equipped with the latest FBS4 (Fourth Generation Frequency Selective System) technology. This advanced security feature enhances vehicle security by using encrypted communication between the key fob and the car’s electronic systems. However, despite its sophistication, various factors can disrupt this communication, leading to the “Key Not Detected” warning.
This problem can be frustrating for Mercedes owners as it can prevent the vehicle from starting or unlocking, thus immobilizing the car. Several potential causes can trigger this issue, ranging from a depleted key fob battery to more complex electronic malfunctions. Understanding these causes and knowing how to address them is crucial for ensuring that your Mercedes operates smoothly.
This guide will explore the common reasons behind the key not recognized warning, outline steps to replace and reset the key fob battery, and provide recommendations on what to do if the problem persists. By following these guidelines, you can quickly troubleshoot the issue and restore full functionality to your Mercedes key system.
Mercedes key not recognized : Causes
If your new Mercedes with the latest FBS4 technology says “key not detected,” it could be due to several issues. Here are some potential causes:
Potential Causes:
# Key Battery Depleted
- The battery in your key might be low or completely dead, preventing communication with the vehicle.
# Synchronization Issue
- The key may have lost synchronization with the vehicle.
# Electronic Malfunction
- There could be an electronic issue with either the key or the vehicle’s system.
For More information, check the following link; Mercedes key not working ignition – Case study & solution
# Radio Interference
- Strong radio signals or electronic interference could be disrupting the key’s communication with the car.
Key Not Detected Mercedes E-Class : Troubleshooting
For many owners of modern cars equipped with Keyless Go systems, such as the Mercedes E-Class W213, the convenience of being able to lock, unlock, and start their vehicle without using a traditional key is a significant advantage. However, when error messages like “key not detected” appear on the instrument cluster, accompanied by malfunctioning locking and unlocking, it can quickly become a nightmare.
Recently, a customer who owned a Mercedes E-Class W213 encountered exactly this issue. After thorough diagnosis, a qualified technician identified the source of the malfunction: corrosion at the electrical connector of the Keyless Go computer.
Corrosion, often caused by water penetration during vehicle washing, can lead to electrical interference and faulty connections, resulting in malfunctions in the car’s electronic systems.
In this case, corrosion had compromised the essential electrical connection between the Keyless Go computer and other components of the system, disrupting communication and preventing the correct operation of the keyless locking and starting system.
Fortunately, once the corrosion was cleaned and the electrical connector properly restored, the customer was able to regain normal use of their Keyless Go system, eliminating the key not recognized error message and restoring locking and unlocking functionality without issue.
However, this story underscores the crucial importance of preventive maintenance and vigilance in the face of potentially invisible problems like corrosion. Even the most advanced technologies are not immune to the devastating effects of this natural phenomenon, so it is recommended for owners of vehicles equipped with Keyless Go systems to regularly monitor the condition of their electrical connectors and take measures to prevent corrosion whenever possible.
How to Replace the Key Battery ?
To replace the key battery, follow the next steps;
Step 1 : Remove the Key Insert
- Slide the release switch on the key fob and pull out the mechanical key insert.
Step 2 : Open the Key Fob
- Use the mechanical key or a small flathead screwdriver to gently pry open the key fob casing.
Step 3 : Replace the Battery
- Remove the old battery and insert a new one of the same type (usually a CR2025 or CR2032 battery). Ensure the positive side is facing the correct direction.
Step 4 : Reassemble the Key Fob
- Snap the key fob casing back together and reinsert the mechanical key.
Fore more information, see the next video
How to Reset the Key ?
To reset the key, follow the next steps;
Step 1 : Insert the Key
- Insert the key into the ignition.
Step 2 : Turn the Ignition On and Off
- Turn the ignition to position 2 (do not start the car), then back to 0. Repeat this process three times.
Step 3 : Test the Key
- Remove the key, wait a few seconds, and then try to lock/unlock the car and start the engine.
Mercedes key not detected after battery change
If you’re encountering the issue of Mercedes key not detected after battery change, there could be several potential reasons behind it:
- Battery Installation Error: Ensure that the new battery is installed correctly, with the positive and negative sides aligned properly. Even a slight misalignment can prevent the key from being detected.
- Key Synchronization: Sometimes, after a battery change, the key may need to be synchronized with the vehicle’s system again. Refer to your vehicle’s owner manual for instructions on how to perform this synchronization process.
- Faulty Battery: Although rare, it’s possible that the new battery itself is faulty or of low quality, which could lead to inadequate power supply to the key fob’s electronics.
- Key Fob Damage: Check the key fob for any physical damage or signs of wear and tear that could be affecting its functionality. If the key fob is damaged, it may need to be repaired or replaced.
- Electronic Interference: Strong radio signals or electronic interference in the vicinity can disrupt communication between the key fob and the vehicle’s receiver, leading to detection issues.
- Vehicle Battery Issues: In some cases, if the vehicle’s battery is weak or failing, it may affect the power supply to the keyless entry system, causing detection problems.
- Faulty Keyless Entry System: There could be an underlying issue with the vehicle’s keyless entry system itself, such as a malfunctioning receiver or transmitter, which may require professional diagnosis and repair.
To address this issue, start by double-checking the battery installation and attempting to synchronize the key with the vehicle according to the manufacturer’s instructions. If the problem persists, consider consulting a qualified technician or contacting a Mercedes-Benz dealership for further assistance and diagnostic testing.
Additional Steps:
- Check for Interference:
- Move away from any potential sources of radio interference and try again.
- Use the Backup Key:
- If you have a spare key, try using it to determine if the problem is with the original key or the car.
- Consult the Manual:
- Refer to your vehicle’s owner manual for specific instructions related to your model.
- Contact a Dealer:
- If the issue persists, contact a Mercedes-Benz dealer or a qualified technician for further diagnosis and assistance. They can reprogram the key or diagnose any deeper electronic issues with your vehicle.