2020 GMC Sierra 1500: Rear window leaking
Common wear/failure (not a recall)
Symptoms
Owners of the 2020 Sierra 1500 report: rear window leaking. CarComplaints.com lists 1 owner complaints, average mileage 22,400 miles.
NHTSA has 15 owner complaints for the 2020 Sierra 1500 in this area. Examples:
- NHTSA complaint ODI #11771040 (filed 10/14/2026): “The contact owns a 2020 gmc sierra 1500. the contact noticed an abnormal odor inside the vehicle. upon inspection, the contact observed that the roof, rear seats, and rear carpet were saturated with water. the vehicle was taken to the dealer, where the contact…”
- NHTSA complaint ODI #11726576 (filed 03/23/2026): “The frame of the back window is cracking allowing water to come in through the back glass. this is causing the headliner and other components such as air bags and other electrical components to get wet and damaged. this could cause risk of fire or failure of …”
Likely causes
Sources do not establish a single root cause; diagnosis is needed. Owner-reported fixes are listed below.
Fix, in plain English
Most common owner-reported solutions on CarComplaints.com: none clearly reported. Check for open recalls and extended warranty coverage with a dealer before paying out of pocket.
DIY difficulty: Moderate
Leaks can often be traced with a water test and resealed; glass replacement is a pro job. (Our assessment.)
Cost
CarComplaints.com owners report a typical repair cost of about $1,800 (owner-reported average, not a quote).
Typical parts (search links, no affiliate codes)
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