California Lemon Law for Unusual Engine Noise on New Cars

Hearing a strange knock, rattle, or whine from a brand-new engine can be unsettling—and frustrating when the noise keeps coming back after dealer visits. If you’re in California, you may be wondering how the state’s lemon law applies to unusual engine noises, what you should record, and when it’s time to talk to a professional. The overview below is designed to help you understand the basics so you can make informed next steps.

California Lemon Law on Engine Noise in New Cars

California’s lemon law (part of the Song-Beverly Consumer Warranty Act) protects buyers and lessees of new vehicles when a defect covered by the manufacturer’s warranty can’t be fixed after a reasonable number of attempts. “Unusual engine noise” can qualify if it stems from a warrantied defect and substantially impairs the car’s use, value, or safety. Examples may include persistent knocking under load, metallic ticking at idle, whining that rises with RPM, or rattling on cold start—especially if the noise accompanies rough running, power loss, or warning lights.

California also has a legal “presumption” for certain vehicles within the first 18 months or 18,000 miles: if the manufacturer or its authorized dealer has made multiple repair attempts for the same problem (or the car has been out of service for 30 total days), the law presumes the vehicle may be a lemon. That said, claims can still be valid outside this presumption if the defect occurred and was reported within the warranty period. Every situation is unique, and the facts—how often the dealer tried to fix it, what was documented, and how the noise affects driving—matter.

If your new car’s engine noise continues after repeated visits, the remedies under California law can include a repurchase or replacement by the manufacturer, plus certain incidental costs, depending on the facts and the law. However, outcomes vary, and this information isn’t legal advice. The most important step is to track the issue carefully and seek guidance early so you understand your rights under your warranty and California law.

What to Document and When to Contact ZapLemon

Start by documenting the noise consistently. Note the date, mileage, conditions, and frequency: cold start versus warm, uphill versus flat, AC on or off, specific speeds or RPMs, and whether any warning lights appear. If safe to do so, record a short audio or video clip that captures the sound. Keep all dealer repair orders and invoices—even if they say “could not verify concern”—and ask the service advisor to describe your complaint in your own words on the repair order.

Track repair attempts and downtime. Write down each visit for the same noise, the diagnosis (if any), and the parts replaced. Ask the dealer whether there are related Technical Service Bulletins (TSBs) or software updates and request printouts of diagnostic codes or test results. Use the fuel grade your owner’s manual specifies and avoid engine modifications while the issue is being evaluated, as changes can complicate warranty coverage questions.

Consider contacting ZapLemon if the dealer has made multiple attempts to repair the engine noise, if your car has been in the shop for extended periods, if you’re nearing the end of your warranty, or if the manufacturer has denied your concerns as “normal” despite evidence of a persistent issue. It can also be helpful to reach out before agreeing to a trade-in or any proposed resolution from the manufacturer so you understand your options. A consultation can clarify timelines, documentation best practices, and how California’s lemon law may apply to your situation.