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.
Automakers increasingly fix and change vehicles with over-the-air (OTA) and dealer-installed firmware updates. When those updates are incorrect or buggy, they can cause new problems that keep a car in the shop or create serious safety concerns. If you’re in California and dealing with repeated software-related issues, you may be wondering how the Lemon Act (California’s Lemon Law) applies to faulty firmware updates.
California Lemon Law and Faulty Firmware Updates
Modern cars run on code as much as they do on fuel. Firmware updates touch critical control modules—engine and transmission computers, braking and stability systems, battery management in EVs, infotainment and cameras, and advanced driver assistance systems (ADAS). A bad update can cause symptoms like stalling after an ECU reflash, sudden loss of power steering assist, phantom braking or lane-keep malfunctions, dead 12V or high-voltage batteries, inoperative backup cameras, or a vehicle that will not start or charge after an OTA push.
California’s Lemon Law—formally the Song-Beverly Consumer Warranty Act—requires manufacturers to repair warranty-covered defects within a reasonable number of attempts. While every situation is fact-specific, the California Lemon Law “presumption” generally applies within the first 18 months or 18,000 miles if: the manufacturer has made at least four attempts to fix the same problem; or two attempts for a defect that could cause death or serious injury; or the car has been out of service for repairs for 30 or more total days. Software and firmware defects count as “defects” just like mechanical ones when they substantially impair use, value, or safety.
If an incorrect firmware update causes persistent issues that the dealer can’t resolve—despite reflashes, rollbacks, module replacements, calibrations, or patches—that pattern may fit the framework of a lemon claim. Potential remedies under the law can include a repurchase, replacement, or a negotiated cash-and-keep outcome, depending on circumstances. Because outcomes depend on facts, timing, mileage, and warranty coverage, a consultation is the best way to understand options for your specific situation.
How to Document Repairs and Protect Your Rights
Good documentation is your best ally with software-related vehicle problems. Ask for a printed or emailed repair order every time you visit the dealer, and make sure it includes the date, mileage in and out, your stated concern, the technician’s diagnosis, firmware or calibration version numbers, and the exact repairs performed. Keep all loaner agreements, tow receipts, and any emails or texts with the service department about OTA pushes or pending patches.
Keep a simple log at home, too. Note when an OTA update was installed or declined, what you saw on the screen, any warning lights or messages, and how the car behaved (for example, “vehicle would not shift out of park after v.2025.10.3 update”). Photos or short videos of error messages, instrument cluster alerts, and malfunctioning features can be very helpful. If the issue is intermittent, capture whenever it happens and record weather, speed, and battery/fuel level if relevant.
Take practical steps that support your record without jeopardizing coverage. Avoid unauthorized modifications or third-party coding tools that could complicate a warranty claim. Ask the dealer to test drive with you to reproduce the problem and to note all related technical service bulletins (TSBs) or recalls. If multiple visits do not resolve the issue, consider escalating with the manufacturer’s customer care to open a case number. At any point, you can contact ZapLemon to discuss whether your pattern of firmware-related defects may fit California’s Lemon Law framework.
Need a case-specific review?
Use the case-review form to share the warranty, repair orders, dates, mileage, and supporting facts an attorney would need to evaluate, or call (844) 927-5366.
Attorney advertising. General information is not legal advice and does not create an attorney-client relationship. No result is promised or guaranteed.