Start with the records. Repair orders, warranty documents, mileage, and days out of service are more useful than general assumptions about whether a vehicle qualifies.
Blind spot monitoring (BSM) is supposed to act like a second set of eyes, warning you about vehicles you can’t see. When it malfunctions—false alarms, late alerts, or no alert at all—it can be frustrating and unsafe. If you’re in California and your vehicle’s BSM won’t stay fixed under warranty, the California Lemon Law may provide remedies. Below, ZapLemon explains how BSM defects fit into the law and how to document repair attempts the right way.
Blind Spot Monitoring Defects Under CA Lemon Law
Blind spot monitoring is part of your vehicle’s advanced driver assistance systems (ADAS). It typically uses radar sensors mounted behind the rear bumper, along with cameras and software, to detect vehicles in adjacent lanes. Common symptoms include the amber mirror icon not lighting when a car is in your blind spot, repeated false warnings when no one is there, a “Blind Spot Monitor/Driver Assist Unavailable” message, or the system shutting off in rain or at highway speeds. These issues can stem from faulty sensors, miscalibrated modules after a bumper repair, wiring faults, or buggy software.
California’s Lemon Law (the Song-Beverly Consumer Warranty Act) may apply when a defect covered by the manufacturer’s warranty substantially impairs the vehicle’s use, value, or safety—and the manufacturer or its dealer can’t fix it after a reasonable number of attempts. There’s a legal “presumption” that can help consumers if, within the first 18 months or 18,000 miles, either the same non-safety defect is subject to multiple repair attempts, a serious safety defect is attempted at least twice, or the vehicle is out of service for 30 or more days. Even if your case doesn’t fit the presumption, you may still have rights under the law. Because BSM is a safety feature, ongoing failures can be more than an annoyance—they can raise safety concerns that courts and manufacturers take seriously.
Real-world examples we see include repeated sensor replacements that don’t resolve phantom alerts, brief fixes that relapse after a software update, and systems that only fail in certain conditions (nighttime, rain, heavy traffic) making them “intermittent” and hard to duplicate on a quick test drive. If your dealership keeps returning the car with “no trouble found,” or the warning light and chimes keep coming back, it can help to build a clear paper trail. Lemon Law remedies can include repurchase or replacement, but results depend on facts and timelines—no outcome is guaranteed. A consultation with a California Lemon Law attorney is the best way to understand your options based on your specific situation.
How to Document Blind Spot Monitoring Repairs
Start documenting the first time the issue appears. Note the date, mileage, weather, traffic, and speed. If it’s safe, capture short videos that show both the mirror indicator/cluster and the lane next to you—this helps show false negatives (no alert despite a car present) or false positives (alert with no car). Write down the exact warning message you see (“Blind Spot Monitor Unavailable,” “Service Driver Assist,” etc.). Avoid clearing dashboard alerts or disconnecting the battery before service; stored fault codes can be critical evidence.
At the dealership, describe the concern in everyday terms and ask the advisor to put your words on the repair order: for example, “BSM fails to alert at highway speeds; false alerts in left mirror; system disables in light rain.” If the problem is intermittent, ask for a test drive with a technician so they can experience it. Each time you pick up the car, request a copy of the final repair invoice showing concern, cause, and correction, plus any calibration reports, part numbers replaced, and software version numbers. If the dealer performs a radar/camera calibration, ask for pre- and post-calibration printouts. Keep records of loaner vehicles and days out of service.
Between visits, keep a simple log of occurrences: date, mileage, conditions, and what happened. Check for recalls and technical service bulletins (TSBs) on NHTSA.gov; if a TSB applies, ask the dealer to perform it and to note it on the repair order. Avoid aftermarket bumper covers, wraps, or brackets near the sensors, and document any body work or windshield replacement that could affect ADAS calibration. If the problem persists, open a case with the manufacturer’s customer assistance line and record your case number. Consistent, detailed documentation can help you and your lawyer evaluate whether your BSM issues may qualify under California’s Lemon Law.
This article is for informational purposes only, is not legal advice, and reading it does not create an attorney–client relationship. Attorney advertising. Every situation is different, and past results do not guarantee future outcomes. If you’re dealing with repeated blind spot monitoring problems under warranty and want to understand your options under California’s Lemon Law, contact ZapLemon to request a consultation via our website or by phone. We’re here to explain the process and help you take the next step.
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Attorney advertising. General information is not legal advice and does not create an attorney-client relationship. No result is promised or guaranteed.