The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2020 ES 350 Blind Spot Monitor (BSM) Malfunction

0

Mike T. · rep 0 · May 22, 4:43 AM · 1 replies · solved · Question

Vehicle: 2020 Lexus ES 350 Luxury

Hi everyone,

I'm having a problem with my 2020 Lexus ES 350 Luxury trim. The Blind Spot Monitor (BSM) system has stopped working correctly. I keep getting a 'BSM System Malfunction' message on the dash, and the indicators in the side mirrors don't light up when there's a car in my blind spot.

It started happening intermittently, but now it seems to be a constant issue. I've checked the settings in the infotainment system, and BSM is definitely turned on. I haven't had any accidents or bumps to the rear bumper area where the sensors are located.

Has anyone else experienced this with their ES 350 or another Lexus model? Is this something I can troubleshoot myself, or does it require a trip to the dealer?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:43 AM

0

ClearTheCode admin answer:

A 'BSM System Malfunction' message on your 2020 Lexus ES 350 indicates an issue with the radar sensors or associated wiring/modules. This is a safety-critical system, so addressing it promptly is important.

Common Causes:

  1. Sensor Obstruction: Even without an accident, dirt, mud, snow, or ice on the rear bumper where the BSM radar sensors are located can block their signal. Ensure the bumper corners are clean.
  2. Wiring Issues: A loose or corroded connection to one of the BSM radar sensors (typically located behind the rear bumper fascia) can cause intermittent or permanent malfunctions.
  3. Sensor Malfunction: The radar sensor unit itself can fail internally. This is less common but does happen.
  4. Module Communication Error: The BSM control module might be experiencing a communication error with other vehicle systems.
  5. Software Glitch: Sometimes, a simple reset or software update can resolve the issue.

Diagnostics:

  • Visual Inspection: Carefully inspect the rear bumper corners for any visible damage, dirt, or debris covering the sensor areas.
  • OBD-II Scan: A professional diagnostic scan tool will be able to read specific trouble codes related to the BSM system. Common codes might include:
    • B1580: Blind Spot Monitor System Malfunction
    • U0121, U0122: Lost Communication with ABS/VSC Control Module (if related to wheel speed sensors)
    • Codes specific to the left or right BSM sensor (e.g., open circuit, short circuit).

When to See a Shop:

If cleaning the sensor areas doesn't resolve the issue, it's best to take your Lexus to a dealership or a reputable independent shop. They have the specialized diagnostic tools to:

  • Read and interpret the specific BSM trouble codes.
  • Test the functionality of each radar sensor.
  • Inspect the wiring and connectors for continuity and corrosion.
  • Perform any necessary sensor recalibration or software updates.

Attempting to access the sensors behind the bumper without proper knowledge can inadvertently cause more damage.

Menu

Help & account