GM over-the-air update 661.20
What it saysImprovements to interior audio quality and volume consistency. NHTSA’s full summary ↓
GM filed this with NHTSA as an over-the-air update dated Jul 24, 2026, received Apr 1, 2026 — 21 documents under this number. It names 37 model years across Chevrolet, GMC and Cadillac (2024–2027). An over-the-air update is not a safety recall — there is no NHTSA campaign number and no federal requirement — but it is usually work the manufacturer pays for on the vehicles it names; the dealer checks the VIN against the manufacturer’s list.
One page for every brand it was filed under. Each brand’s bulletins: Chevrolet · GMC · Cadillac.
Get the next GM bulletin for your model by email Weekly, only when something new is filed. Nothing else; one-click unsubscribe.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communication• Improvements to interior audio quality and volume consistency. • Improves traction and stability control when accelerating or on uneven terrain. • Improves braking and stopping performance on low-traction surfaces. • Fixes for active cabin ventilation. • Fixes to help ensure proper functionality for heating and cooling features. • Improvements to night mode lights for shifting gears. • Fixes for Daytime Running Lamps turning on when set to Off. • Fixes for speed threshold for pedestrian alerts. • Improvements to the performance of Automatic Emergency Braking and Adaptive Cruise Control braking. • Fixes to help ensure proper functionality of Forward Collision Alert and availability of driver assistance features. • Fixes to help protect battery life. • Improvements to provide more accurate speed limit detection on the driver’s display. • Fixes to help ensure driver assistance features remain functional when the windshield freezes. • Fixes to help ensure accurate driver display messages and alerts.
Documents filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 661.20 | Over-the-air update | Jul 24, 2026 | 11035347 | PDF, 196 KB |
| 661.20 | Over-the-air update | Jun 18, 2026 | 11034066 | PDF, 192 KB |
| 661.20 | Over-the-air update | Jun 10, 2026 | 11034055 | PDF, 189 KB |
| 661.20 | Over-the-air update | Jun 8, 2026 | 11034048 | PDF, 194 KB |
| 661.20 | Over-the-air update | Jun 2, 2026 | 11033769 | PDF, 189 KB |
| 661.20 | Over-the-air update | May 30, 2026 | 11033005 | PDF, 186 KB |
| 661.20 | Over-the-air update | May 26, 2026 | 11032915 | PDF, 190 KB |
| 661.20 | Over-the-air update | May 1, 2026 | 11031828 | PDF, 190 KB |
| 661.20 | Over-the-air update | Apr 28, 2026 | 11031821 | PDF, 203 KB |
| 661.20 | Over-the-air update | Apr 23, 2026 | 11031769 | PDF, 190 KB |
| 661.20 | Over-the-air update | Apr 22, 2026 | 11031816 | PDF, 194 KB |
| 661.20 | Over-the-air update | Apr 21, 2026 | 11031774 | PDF, 193 KB |
| 661.20 | Over-the-air update | Apr 16, 2026 | 11031776 | PDF, 191 KB |
| 661.20 | Over-the-air update | Apr 14, 2026 | 11031789 | PDF, 194 KB |
| 661.20 | Over-the-air update | Apr 14, 2026 | 11031788 | PDF, 195 KB |
| 661.20 | Over-the-air update | Apr 10, 2026 | 11031790 | PDF, 192 KB |
| 661.20 | Over-the-air update | Apr 2, 2026 | 11030537 | PDF, 196 KB |
| 661.20 | Over-the-air update | Mar 27, 2026 | 11030524 | PDF, 199 KB |
| 661.20 | Over-the-air update | Mar 21, 2026 | 11030538 | PDF, 195 KB |
| 661.20 | Over-the-air update | Mar 2, 2026 | 11030460 | PDF, 196 KB |
| 661.20 | Over-the-air update | Feb 23, 2026 | 11030459 | PDF, 192 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themChevrolet 17 model years
GMC 10 model years
Also filed against model years this site has no page for: 2026 GMC Hummer EV Pickup; 2026 GMC Hummer EV SUV.
Cadillac 10 model years
A vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
Email me new GM bulletins for one of these models
A weekly email, sent only in a week when GM files something new with NHTSA for the model you pick — service bulletins, campaigns, warranty extensions, over-the-air notices, every model year. Nothing else is sent; one-click unsubscribe in every message. Separate from recall alerts.
What owners reported
Source: NHTSA complaint databaseOwners of the 35 model years this bulletin names have filed 2,937 complaints with NHTSA since 2015.
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Chevrolet, GMC and Cadillac, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is GM 661.20 a recall?
No. A over-the-air update is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 661.20 repair free?
A over-the-air update is usually paid by the manufacturer on the vehicles it names, within the terms and time limit the document sets; the dealer checks the VIN against the manufacturer’s list.
Which vehicles does 661.20 cover?
The manufacturer filed it against 37 model years across 3 brands (Chevrolet, GMC and Cadillac): 2025 Cadillac CT4, 2025 Cadillac CT5, 2026 Cadillac Celestiq, 2026 Cadillac Escalade, 2024 Cadillac Escalade, 2026 Cadillac Lyriq and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.