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2020 Mazda 3 Blind Spot Monitoring System Malfunction

0

Mike T. · rep 0 · May 22, 4:50 AM · 1 replies · solved · Question

Vehicle: 2020 Mazda 3 Premium

Hi all,

I'm having an issue with my 2020 Mazda 3 Premium. Recently, the Blind Spot Monitoring (BSM) system has been acting up. I keep getting a 'BSM System Malfunction' message on my display, and the warning lights in the side mirrors don't illuminate when they should.

It seems to happen intermittently, sometimes it works fine for a bit, then the error pops up again. I've tried cleaning the rear bumper where the sensors are located, thinking it might be dirt or debris, but that hasn't helped.

Has anyone else experienced this with their Mazda 3? Is this a common sensor issue, or could it be something more serious like wiring? Any suggestions on what I should look into?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:50 AM

0

ClearTheCode admin answer:

An intermittent 'BSM System Malfunction' on your 2020 Mazda 3 Premium is a common concern, often pointing to issues with the radar sensors themselves or their connections.

  1. Sensor Obstruction/Damage:

    • Location: The BSM system uses radar sensors typically located behind the rear bumper on each side. Even if you've cleaned the exterior, internal damage or a slight misalignment of the sensor itself can cause issues.
    • Inspection: Visually inspect the rear bumper area for any signs of impact, even minor ones, that might have shifted or damaged the sensors. Ensure no aftermarket accessories are blocking the sensor's field of view.

  2. Wiring and Connectors:

    • Vibration/Corrosion: Over time, wiring harnesses and connectors can become loose, corroded, or damaged due to vibration or exposure to elements. A poor connection to one of the BSM radar units could cause intermittent errors.
    • Check: While difficult without removing the bumper, a professional can check the integrity of the wiring and connectors leading to the BSM sensors.

  3. Module Malfunction:

    • Internal Fault: Less common, but the BSM control module itself (often integrated with the sensors) could have an internal fault.

  4. OBD-II Codes:

    • A diagnostic scan tool will likely reveal specific trouble codes related to the BSM system. Common codes might include B13D3 (BSM System Malfunction), C1A60 (Front Radar Sensor Malfunction) (though BSM is rear, sometimes systems are linked), or other manufacturer-specific codes indicating a fault in one of the radar units or its communication.

When to See a Shop: Since this is a safety-critical system, and given the intermittent nature, it's highly recommended to have your Mazda 3 inspected by a Mazda dealership or a specialized automotive electrical shop. They have the specific diagnostic tools (like Mazda's M-MDS) to read the precise BSM system codes, perform sensor calibration if needed, and accurately diagnose whether it's a sensor, wiring, or module issue. Driving with a malfunctioning BSM system reduces your situational awareness and safety.

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