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2022 S500 Keyless Go Not Detecting SmartKey

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Heather Y. · rep 0 · May 22, 4:16 AM · 1 replies · solved · Question

Vehicle: 2022 Mercedes-Benz S500

Hi everyone,

I'm having an intermittent but persistent issue with my 2022 Mercedes-Benz S500 (W223). The Keyless Go function often fails to detect my SmartKey. This means I can't unlock the doors by touching the handle, and sometimes I can't start the car by just pressing the start button – I have to place the key in the designated spot in the center console.

I've tried both of my keys, and they both exhibit the same behavior. I've also replaced the battery in both SmartKeys, but that didn't resolve the problem. It seems to happen more frequently when the car has been sitting for a while, but it's not consistent.

Is this a common issue with the W223 S-Class? Could it be a faulty antenna, a control module, or perhaps interference? Any insights would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:16 AM

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ClearTheCode admin answer:

The Keyless Go system in your 2022 Mercedes-Benz S500 is designed for convenience, and when it malfunctions, it can be quite frustrating. This system relies on a network of antennas and control modules to detect the presence and location of your SmartKey. Intermittent detection issues often point to specific electrical problems.

Common Causes for Keyless Go Malfunctions:

  1. SmartKey Battery: While you've replaced them, ensure they are high-quality batteries and correctly installed. A weak signal from the key is the simplest cause.
  2. Vehicle Antenna Issues: The S-Class has multiple antennas located around the vehicle (door handles, trunk, interior) that communicate with the SmartKey. A faulty or obstructed antenna, or its wiring, can lead to poor detection in specific areas.
  3. Keyless Go Control Module: The central control unit responsible for processing the key's signal and authorizing access/start can malfunction. This module is complex and can develop internal faults.
  4. Radio Frequency Interference: While less common, strong external radio frequency interference (e.g., from nearby cell towers, power lines, or even other electronic devices in the car) can sometimes disrupt the key's signal.
  5. Vehicle Battery Voltage: Low vehicle battery voltage, even if not completely dead, can sometimes cause non-essential systems like Keyless Go to behave erratically.

Troubleshooting Steps:

  1. Test in Different Locations: Try using Keyless Go in various physical locations to rule out external interference.
  2. Check for Recalls/TSBs: Mercedes-Benz may have issued technical service bulletins (TSBs) or recalls related to Keyless Go system updates or known issues for your specific model year.
  3. Inspect Door Handles: Visually check the door handles for any physical damage or debris that might obstruct the sensor within the handle.

When to See a Shop:

Since you've already replaced the key batteries and the issue persists with both keys, it's highly advisable to take your S500 to a Mercedes-Benz dealership. They have specialized diagnostic equipment (XENTRY/DAS) that can:

  • Read specific fault codes from the Keyless Go control module and other related modules (e.g., EIS/EZS - Electronic Ignition Switch).
  • Perform diagnostic routines to test the functionality of individual antennas and the control module.
  • Identify if a software update is available for the Keyless Go system or if a hardware component (antenna, module) needs replacement. This is a complex system, and professional diagnosis is essential for accurate repair.
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