GM Brake Master Cylinder Lawsuit: What Owners Know

Two federal lawsuits say the master brake cylinder in five 2025 GM models can fail. No settlement or claim form exists.

The GM brake master cylinder lawsuit is two proposed class actions pending in the U.S. District Court for the Eastern District of Pennsylvania, and neither one has a settlement or a claim form. The suits name 2025 model year Chevrolet Traverse, GMC Acadia, Buick Enclave, Chevrolet Colorado and GMC Canyon vehicles. Each proposed class is limited to buyers in specific states, and no class has been certified.

The first case, Barron v. General Motors LLC, was filed in October 2025. The second, Fehrmann v. General Motors LLC, was filed on October 6, 2026. Both lawsuits make allegations that remain unproven, and no court has found the vehicles defective.

Is There a GM Brake Master Cylinder Settlement?

There is no GM brake master cylinder settlement, and there is no claim form to file. No class has been certified in either lawsuit, according to Open Class Actions. Nobody can promise a payout from a case with no settlement.

The two lawsuits name the same five vehicles: the 2025 Chevrolet Traverse, GMC Acadia, Buick Enclave, Chevrolet Colorado and GMC Canyon. Barron proposes a class of buyers in New York, Pennsylvania and Missouri. Fehrmann proposes classes of buyers and lessees in Illinois, Kentucky, Michigan, Ohio and Texas.

The first thing to do is keep records. Save every repair order, invoice and receipt tied to your brakes, and write down the date, the mileage and the warning messages you saw. You can also search complaints and recalls for your vehicle on the National Highway Traffic Safety Administration (NHTSA) website.

Which Vehicles and Which Owners

The lawsuits cover 2025 model year vehicles only. Proposed classes cover buyers (and, in Fehrmann, lessees) in eight states. Neither case seeks a nationwide class. The table below shows which vehicles appear in the suits.

Each proposed class is limited to buyers, or buyers and lessees, in specific states. The state lists come from Open Class Actions' report.

CarComplaints.com reports that the refiled Barron complaint added Missouri, and that Sergei Lemberg is counsel for the Barron plaintiffs. A separate GM case about a different defect is covered in our guide to the GM coolant leak class action.

What the Lawsuits Allege

The lawsuits allege that internal seals in the master brake cylinder can fail and let brake fluid leak. The plaintiffs say that leak can cause a sudden loss of hydraulic pressure and reduced braking. In some cases, they claim, the failure came weeks or months after delivery.

The complaints describe a set of warning signs. The plaintiffs allege a red Brake warning light, an anti-lock braking system (ABS) warning light and a "Service Brake System" message. They allege the pedal either goes hard or sinks toward the floor, causing partial or total loss of braking. If your vehicle shows any of these signs, have it inspected by a qualified shop or a GM dealer.

The plaintiffs also claim GM knew about the problem before the vehicles were sold. They point to pre-sale testing, warranty and dealer data, NHTSA complaints, and a "higher-than-expected" number of replacement orders. Fehrmann quotes more than two dozen NHTSA complaints from Traverse and Acadia owners, but neither source gives a total complaint count.

The sources list the following claims and relief:

• Fehrmann brings 17 claims seeking damages, restitution, and repair or replacement with extended warranties.
• Fehrmann also asks for an order requiring GM to recall and repair the vehicles, plus attorneys' fees.
• Barron brings 13 claims after the plaintiffs withdrew three state lemon law claims. The relief Barron seeks is not listed in the published sources.

What GM Has Said and Done

GM has issued a service update, but among the 2025 models in the suits it covers only the Buick Enclave.

GM Service Update N242482170, dated December 2024 per Open Class Actions, covers 2024 Chevrolet Traverse and 2025 Buick Enclave vehicles. It says an internal cartridge seal in the eBoost module may be missing, and it tells dealers to replace the master cylinder. GM has not issued a safety recall or dealer bulletin covering the other 2025 models in the suits.

In Barron, GM argues that the three plaintiffs do not own a vehicle named in that service update. The plaintiffs answer that the same components are in their vehicles. CarComplaints.com reports that GM replaced the failed master cylinders for free.

Where the Cases Stand

Barron is in the discovery phase, and GM has not yet responded in Fehrmann, per Open Class Actions. In May 2026, Judge John F. Murphy denied GM's motion to dismiss Barron. He also denied GM's motion to compel arbitration for two of the buyers.

The two cases may be coordinated or consolidated, but the court has not decided that. No class is certified, no settlement exists, and no court has found the vehicles defective.

What to Document Now

Owners of a named vehicle can keep a paper trail of every brake problem and repair.

1. Keep every repair order, invoice and receipt that mentions the brakes or the master cylinder.
2. Write down the date, the mileage and the exact warning messages each time the problem happens.
3. Take photos of the dashboard showing the Brake light, the ABS light or the Service Brake System message.
4. Search complaints and recalls for your vehicle identification number (VIN) on the NHTSA website.
5. Ask a GM dealer whether Service Update N242482170 or any open recall applies to your VIN.
6. File a complaint with NHTSA if the brake problem happened to you.

Lemon law rights vary by state. Our explainer on lemon law compensation eligibility covers how those claims work.

If a Settlement Comes

You do not need to take any action today to remain a possible class member, and you cannot join a proposed class action in advance. If a class is certified or a settlement is reached, the court and a settlement administrator would post the notice and claim process. The published sources do not describe how owners would be notified.

Scammers copy headlines about lawsuits. No real lawsuit charges a fee to be a possible class member, and nobody can promise a payout from a case with no settlement. For the general process, see our overview of how class action settlements work.

This page describes allegations in pending lawsuits. It cannot tell you whether your vehicle is defective or whether you will ever receive money. More pending consumer cases appear on our class actions hub. Keep a file of repair orders, receipts and photos (see the steps above).

Frequently Asked Questions

Is there a GM brake master cylinder class action settlement?

No. No class has been certified, no settlement exists, and there is no claim form. Both lawsuits are pending in the U.S. District Court for the Eastern District of Pennsylvania, and no court has found the vehicles defective.

Which GM vehicles are named in the brake lawsuits?

The lawsuits name 2025 model year Chevrolet Traverse, GMC Acadia, Buick Enclave, Chevrolet Colorado and GMC Canyon vehicles. Barron covers buyers in New York, Pennsylvania and Missouri. Fehrmann covers buyers and lessees in Illinois, Kentucky, Michigan, Ohio and Texas.

What are the symptoms of a failing master brake cylinder?

The lawsuits allege drivers see a red Brake warning light, an ABS warning light and a Service Brake System message. They say the brake pedal either goes hard or sinks toward the floor, causing partial or total loss of braking. If your brakes show any of these signs, have the vehicle inspected by a qualified shop or a GM dealer.

Has GM recalled these vehicles for the brake problem?

GM Service Update N242482170 covers 2024 Chevrolet Traverse and 2025 Buick Enclave vehicles and tells dealers to replace the master cylinder. GM has not issued a safety recall or dealer bulletin covering the other 2025 models in the suits.

Can I join the lawsuit?

You do not join a proposed class action in advance, and being a possible class member requires no action today. If a class is certified or a settlement is reached, the court and a settlement administrator would post the notice and claim process. The published sources do not describe how owners would be notified.

How do I check NHTSA for complaints and recalls on my vehicle?

Go to NHTSA's website at nhtsa.gov and search complaints and recalls using your vehicle identification number (VIN). If the brake problem happened to you, you can file a complaint with NHTSA.