Answer
Dec 23, 2025 - 02:45 PM
That light refers to the Collision Prevention Assist system (often called CPA). When it stays on, it means the forward-facing radar sensor is offline or malfunctioning. Before you worry about an expensive repair, here is the technical breakdown of the most common culprits we see on the 2014 models:
- Sensor Obstruction: The radar sensor is located behind the Mercedes Star in the front grille. Even a thin layer of dirt, ice, mud, or bug splatter can block the signal. Give that area a thorough cleaning first.
- License Plate Interference: If your front license plate bracket is loose, warped, or mounted too high, it can interfere with the radar's field of view, triggering a false positive or a system fault.
- Wiring or Sensor Failure: On early CLA models, the wiring harness connecting to the radar sensor (behind the bumper) is prone to corrosion or chafing. It’s also possible the sensor itself has failed or simply needs a software calibration update.
Because this system ties into the brakes and safety features, you don't want to guess.
This OEM software contains the complete troubleshooting procedure for the Collision Prevention Assist system. It will show you exactly how to inspect the wiring, test the sensor resistance, and follow the factory diagnostic tree to pinpoint the issue—whether it's a simple cleaning job or a part that needs swapping.
