U.S. District Judge David Lawson has certified class actions in 26 U.S. states for owners of select General Motors models, accusing the carmaker of knowingly selling vehicles with faulty transmissions.

The lawsuit alleges that approximately 800,000 vehicles are fitted with faulty Hydra-Matic 8L90 and 8L45 8-speed automatic transmissions. They consist of the 2015-2019 Chevrolet Silverado, 2017-2019 Chevrolet Colorado, 2015-2019 Chevrolet Corvette, 2016-2019 Chevrolet Camaro, 2015-2019 Cadillac Escalade and Escalade ESV, 2016-2019 Cadillac ATS, ATS-V, CTS, CT6, and CTS-V models, 2015-2019 GMC Sierra, Yukon, Yukon XL and Yukon Denali XL, as well as the 2017-2019 GMC Canyon.

The plaintiffs claim the automatic transmissions in question will “slip, buck, kick, jerk and harshly engage” and that vehicles have become unsafe to drive, particularly given the sudden or delayed acceleration they may provide.

 Judge Certifies Class Actions For Over 800,000 GM Vehicles With Faulty Transmissions

It is alleged that the transmissions have defective automatic transmission fluid that fails to “maintain a positive friction curve over time” causing shudder problems. The transmission is also claimed to have an “inability to purge trapped air due to an insufficient valve body architecture” that causes problems with “harsh shifts.” GM apparently developed a new automatic transmission fluid and replaced it in vehicles that remained unsold on dealer lots but did not deploy this new fluid to vehicles that had already been sold.

Owners claim that GM knew about the defect before selling the vehicles and that they would not have purchased them had they known about the issue.

Read: GM Slapped With A $102.6 Million Verdict In California Over Engine Defect Leading To Excessive Oil Consumption

Judge David Lawson said there was substantial evidence that the car manufacturer had “rapidly accumulated irrefutable evidence of a widespread defect as a result of a years-long — and apparently still ongoing – investigation” but not informed drivers.

The states where the class actions will proceed are Alabama, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Kansas, Kentucky, Louisiana, Maine, Michigan, Minnesota, New Hampshire, New Jersey, New York, North Carolina, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Washington and Wisconsin.

 Judge Certifies Class Actions For Over 800,000 GM Vehicles With Faulty Transmissions