Cadillac bulletin 661.21
Cadillac filed this with NHTSA as a over-the-air update dated May 1, 2026, received Apr 30, 2026, about the unknown or other — 3 documents under this number. It names 3 model years (2024–2025). A 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.
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. • 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 |
|---|---|---|---|---|
| 661.21 | Over-the-air update | May 1, 2026 | 11031923 | not yet checked |
| 661.21 | Over-the-air update | Apr 28, 2026 | 11031827 | not yet checked |
| 661.21 | Over-the-air update | Apr 28, 2026 | 11031812 | not yet checked |
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 themA vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
Common questions
Source: NHTSA, 49 CFR 579.5Is Cadillac 661.21 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 661.21 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 661.21 cover?
The manufacturer filed it against 3 model years: 2025 Cadillac Celestiq, 2025 Cadillac Escalade, 2024 Cadillac Lyriq. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.