GMC Sierra HD Lemon Law

GM recalled roughly 462,000 diesel trucks — including 2020–2022 Sierra 2500HD and 3500HD models with the 10-speed Allison-branded automatic — over a transmission control valve that can wear over time (NHTSA 24V797). The failing valve causes harsh, jerking shifts and, in rare cases, can briefly lock up the rear wheels. The recall remedy is a transmission control module software reflash rather than a new valve body, so many owners report the harsh shifting and shudder return after the update.

Sierra HD owners also report a range of Duramax diesel complaints — emissions and DEF (diesel exhaust fluid) system warnings, limp-mode or reduced-power events, regeneration faults, fuel system issues, plus infotainment and electrical glitches. Because these trucks are worked hard, a single unresolved defect can take the truck off the road for days at a time and cost real money in lost use.

California's Lemon Law can apply when a substantial defect isn't fixed after a reasonable number of repair attempts, or the truck is out of service for an extended period, while under warranty — and you do not need a recall to qualify. Importantly, California's Lemon Law can cover vehicles used for business, not just personal ones: a business vehicle qualifies when it has a gross vehicle weight (curb weight) under 10,000 pounds and the business has five or fewer vehicles registered in California. If your Sierra HD qualifies, you may be entitled to a buyback, replacement, or cash settlement, with GM paying your attorney fees.

A recall is not automatically a lemon — it's the manufacturer acknowledging a defect and offering a free repair. California's Lemon Law (the Song-Beverly Act) comes into play when a substantial defect can't be fixed after a reasonable number of attempts, or when your Sierra HD has been out of service for 30 or more cumulative days.

If your GMC Sierra HD qualifies, you may be entitled to a buyback (a refund of what you've paid, minus a mileage offset), a replacement vehicle, or a cash-and-keep settlement — and GMC pays your attorney fees on a successful claim, so pursuing your case costs you nothing out of pocket.