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2021 TLX Type S: Collision Mitigation Braking System (CMBS) Warning

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Mike T. · rep 0 · May 25, 3:42 AM · 1 replies · solved · Question

Vehicle: 2021 Acura TLX Type S

Hi everyone,

I'm getting a 'Collision Mitigation Braking System Malfunction' warning message on the dash of my 2021 Acura TLX Type S. It also says 'CMBS System Unavailable.' This popped up suddenly yesterday while I was driving, and it hasn't gone away since. There haven't been any bumps or incidents, and the front of the car looks clean.

I rely on these safety features, so it's a bit concerning. Has anyone experienced this with their TLX, especially the Type S model? Could it be a sensor issue, or maybe something more complex with the ADAS module?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:42 AM

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ClearTheCode admin answer:

A 'Collision Mitigation Braking System Malfunction' on your 2021 Acura TLX Type S indicates an issue with one of the critical components of your Advanced Driver-Assistance Systems (ADAS). The CMBS uses a combination of radar (typically behind the Acura emblem) and a camera (mounted at the top of the windshield) to detect potential frontal collisions.

  1. Common Electrical Causes:

    • Blocked Sensor/Camera: Even if the exterior looks clean, sometimes a subtle film, bug splatter, or internal condensation on the camera lens can obscure its view. The radar sensor can also be sensitive to very minor obstructions.
    • Sensor Misalignment: A very minor bump or even a strong pothole hit can sometimes slightly misalign the radar unit or camera, causing it to lose calibration. This is an electrical system reporting an out-of-spec physical alignment.
    • Wiring/Connector Issues: Damaged wiring or a loose/corroded connector to either the radar unit, camera module, or the main ADAS control unit can interrupt communication and trigger a fault.
    • Faulty Sensor/Module: Less frequently, one of the sensors (radar or camera) or the ADAS control module itself can fail internally.
    • OBD-II Codes: CMBS issues will generate specific manufacturer U-codes (e.g., U0300 - Internal Control Module Software Incompatibility, U0100 - Lost Communication With ECM/PCM A) or B-codes related to sensor performance or communication errors.

  2. Initial Checks (DIY):

    • Clean Sensors: Thoroughly clean the area around the Acura emblem on the front grille (where the radar sensor is located) and the windshield area around the camera behind the rearview mirror. Use a soft cloth and glass cleaner for the camera.
    • Check for Visible Damage: Inspect the front bumper and grille area for any signs of impact, no matter how small, that might have affected the radar sensor's mounting.
    • Battery Check: Ensure your car's 12V battery is in good health and fully charged. Low voltage can sometimes cause ADAS systems to temporarily malfunction.

  3. When to See a Shop:

    • If cleaning doesn't resolve the issue, it's imperative to take your TLX Type S to an Acura dealership immediately. ADAS systems are safety-critical.
    • They have specialized diagnostic tools to read the specific ADAS codes, pinpoint the exact faulty component (radar, camera, or module), and perform necessary recalibrations. Many ADAS components require precise alignment and calibration after replacement or repair, which can only be done with dealer-specific equipment.
    • Do not attempt to 'fix' this yourself beyond basic cleaning, as incorrect repair can compromise your vehicle's safety features.
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