GM Water Leak Lawsuit: Silverado and Sierra Rear Sliding Window Leaks, Plus GM Coolant Leak Claims

The trucks in the case have a rear window made of fixed glass and a power sliding glass panel in a plastic frame sealed with urethane. The complaint alleges that the rear sliding window seal can crack or leak, letting water into the rear of the cab, where it can cause mold growth and damage electrical components.

The case is Filiberto Loza Gonzalez v. General Motors, LLC, No. 1:26-cv-02324, in the U.S. District Court for the Eastern District of California, filed June 1, 2026. It claims GM knew of the defect from dealer reports, warranty data, testing, and complaints, did not disclose it, and refuses to pay for repairs once the warranty expires. The plaintiff relies on California's Consumers Legal Remedies Act and Business and Professions Code, and seeks damages and declaratory relief.

These are allegations. GM has not responded on the merits in anything we could review, and no court has found that the windows are defective. The vehicles named are:

• 2019 to 2020 Chevrolet Silverado 1500 and GMC Sierra 1500
• 2020 Chevrolet Silverado 2500 HD and 3500 HD
• 2020 GMC Sierra 2500 HD and 3500 HD

What GM's service bulletin 18-NA-383 says

The lawsuit leans heavily on GM's own dealer instructions. A technical service bulletin tells dealers how to diagnose and fix a known condition. It is not a recall, so the repair is usually free only while the vehicle is under warranty.

GM issued bulletin 18-NA-383, "Water Found in Rear Interior of Cab, Water Leak at Rear Sliding Window," on January 3, 2019, and the complaint says it was revised and expanded 12 times, most recently on March 7, 2023. According to the bulletin as quoted in reporting on the case, the cause may be cracking in the plastic upper rail glass guide of the sliding window or a leak in the primary urethane seal, and dealers are told to remove the roof rear spoiler and apply seam sealer to the top of the window.

The complaint argues that a bulletin covering exactly these trucks, and no others, is an acknowledgment of a classwide problem. GM may argue the opposite: that a bulletin shows it offered a fix and that leaks vary from truck to truck. How a court weighs that will matter at class certification.

The named plaintiff bought his 2019 GMC Sierra 1500 new. According to the complaint as reported, he noticed water coming into the rear of the cab while washing the truck, and at 57,134 miles he took it to a dealer. The dealer confirmed the leak and repaired it using the latest version of bulletin 18-NA-383, but GM would not pay, and he says the repair cost him more than $1,000.

His experience points to the practical signs owners describe with this kind of leak:

• Water or dampness behind the rear seats or on the rear floor after rain or a car wash.
• Stains on the headliner or trim near the rear window.
• A musty smell, visible mold, or fogged glass inside the cab.
• Electrical glitches that start after wet weather.

None of these proves the rear window is the source; door seals, the cab roof, and other openings can leak too. That is why a written dealer diagnosis naming the rear sliding window, ideally referencing the bulletin, is the most useful piece of evidence you can have. A repair order that ties your leak to bulletin 18-NA-383 connects your truck directly to the condition described in the lawsuit.

If you already paid for a repair, do not throw away the old invoice even if it seems small. In many vehicle defect settlements, reimbursement depends on proof of what you paid and when, and records created at the time are far stronger than memories reconstructed years later.

Case	Vehicles	Status
Gonzalez, E.D. Cal. 1:26-cv-02324	2019 to 2020 Silverado, Sierra	Filed June 1, 2026; pending
Dixon, N.D. Ga.	Colorado, Canyon, Traverse, Acadia, Enclave	Filed June 2026; pending

The Gonzalez case is at the pleading stage. The usual next steps are GM's answer or a motion to dismiss, then discovery, then a motion to certify the California class. Car defect class actions often take several years, and many end in settlements that extend warranties rather than pay large sums. See how long class actions take.

As of September 2026, we found no GM water leak settlement, no claim form, and no GM safety recall for the rear sliding window leak on these trucks. Be wary of any site that claims you can file for money now.

The proposed class is limited to California purchasers and lessees of trucks first placed in service after January 3, 2019.

The proposed class is "all persons who purchased or leased" the listed trucks "in California, that were first placed into service after January 3, 2019." That means:

• Likely in the proposed class: California buyers or lessees of the listed trucks, new or used, first put in service after January 3, 2019.
• Not in this class: buyers in other states, owners of models or years not listed, and trucks without the power sliding rear window.
• Strongest facts: a documented leak, a dealer repair under the bulletin, and money you paid after the warranty expired.

If you are outside California, a class limited to California does not cover you, but similar claims may exist under your state's consumer and warranty laws. A new suit could also be filed in another state. For how classes are defined, see how to know if you qualify.

Used truck buyers should pay attention too. The proposed class covers people who "purchased or leased" the listed trucks in California, and the definition as reported is tied to trucks first placed in service after January 3, 2019, not to whether you were the first owner. If you bought a used 2019 or 2020 Silverado or Sierra with a power sliding rear window, check the cab for signs of past water damage and ask for the service history. A prior repair under bulletin 18-NA-383 is a sign the truck had the condition, and it may help you if the leak returns.

No settlement exists, so there is no payout figure. The complaint seeks compensatory, exemplary, and statutory damages. The named plaintiff says he paid more than $1,000 to fix the leak on his 2019 Sierra 1500 at 57,134 miles after the dealer confirmed the leak but would not cover it. Repair costs like that, plus mold remediation and damaged electronics, are what an owner would typically try to recover.

In vehicle defect settlements generally, common remedies are reimbursement of documented repair costs and an extended warranty for the part at issue. Owners who never had a leak often get only the warranty extension. For how these deals are structured, read how class action money is divided.

The Gonzalez complaint relies on 2 California statutes: the Consumers Legal Remedies Act and the Business and Professions Code.

• California Consumers Legal Remedies Act. Bars deceptive practices in consumer sales, including failing to disclose known defects in some circumstances.
• California Business and Professions Code (Unfair Competition Law). Allows restitution for unlawful, unfair, or fraudulent business practices.
• Warranty law. The Song-Beverly Consumer Warranty Act is California's lemon law, and the federal Magnuson-Moss Warranty Act covers written warranties nationwide.
• Lemon laws. Repeated failed leak repairs during the warranty period can support a lemon law claim in any state, separate from the class case.

Concealment cases usually turn on what the manufacturer knew and when. That is why the January 3, 2019 bulletin date matters: the proposed class is limited to trucks first put in service after it.

Water damage claims also touch on insurance. Some owners file with their auto insurer after a leak damages carpet or electronics, and a comprehensive claim may cover sudden water damage, depending on the policy wording. Insurers often exclude gradual leaks and wear, though, so a claim can be denied for the same reason the lawsuit exists: the leak comes from a built-in defect. Keep any insurance denial letter, since it documents your loss and the cause the adjuster identified.

The Dixon case covers 5 models: the Colorado, Canyon, Traverse, Acadia, and Enclave.

Some owners searching for a GM leak lawsuit have a coolant leak, not a water leak. Jonathan Dixon v. General Motors LLC, filed in June 2026 in the Northern District of Georgia, alleges coolant can leak from radiator hose quick connectors early in a vehicle's life and damage the engine. It covers 2023 to 2026 Chevrolet Colorado and GMC Canyon trucks with the L3B 2.7-liter turbo engine, and 2024 to 2026 Chevrolet Traverse, 2024 to 2026 GMC Acadia, and 2025 to 2026 Buick Enclave with the LK0 2.5-liter turbo engine.

The plaintiff says his 2024 Colorado showed a check engine light and a low coolant level at about 44,400 miles and that he paid $489.36 for repairs. The complaint cites GM Special Coverage Program N262546590 for lower radiator hose connector seals on other models and a March 2026 bulletin, PIT6494A, for upper hose connectors on the Colorado and Canyon. If you have one of these vehicles, ask the dealer whether a special coverage program applies before paying. These claims are also unproven.

Bulletin 18-NA-383 has been revised about 12 times, so ask the dealer to use the latest version when diagnosing your truck.

1. Document the leak with dated photos and video, especially after rain or a car wash.
2. Get a written dealer diagnosis and ask whether bulletin 18-NA-383 applies to your truck.
3. Ask for goodwill coverage in writing if you are just outside the warranty, and keep the answer.
4. Save every receipt for window, seal, carpet, mold, and electrical repairs.
5. Watch for mold and electrical problems, and keep records of any health or safety issues.
6. Check for deadlines. Warranty and consumer claims have a statute of limitations, so do not wait years to act.

Other GM pages cover Silverado and Sierra recalls and engine claims. If your GM vehicle leaks and the dealer will not cover the repair, independent attorneys who handle auto defect cases may want to hear about it. A free case review takes about two minutes.