TSB 661.21 — Cadillac, Chevrolet and GMC Software update
661.21 is a software update on file with NHTSA for 6 Cadillac, Chevrolet and GMC models, 2024–2025 model years, filed and re-filed as 3 documents. A TSB is factory repair guidance, not a recall — the repair is not automatically free.
What the bulletin says. • Improvements to the performance of vehicle software updates. • Fixes to help prevent loss of functionality for connectivity features, including maps and Wi-Fi. • Fixes to help prevent erroneous emergency calls from vehicle. • Fixes for deleting digital keys. • Fixes to help…
NHTSA's own summary of the document, quoted from the public manufacturer-communications file.
Worth checking your VIN against. 661.21 is filed as a software update, which unlike an ordinary bulletin can mean free or reimbursed work when a vehicle qualifies. Ask a dealer using the document ID below, and check open recalls separately at nhtsa.gov/recalls.
Vehicles and model years 661.21 names
| Vehicle | Model years |
|---|---|
| Cadillac Escalade | 2025 |
| Chevrolet Colorado | 2024 |
| Chevrolet Suburban | 2025 |
| Chevrolet Tahoe | 2025 |
| GMC Canyon | 2024 |
| GMC Yukon | 2025 |
Every document filed under 661.21
Manufacturers re-issue a bulletin as the repair changes, and file separate copies for technicians and for owners. All of them carry the same number.
| Document ID | Filed | Type |
|---|---|---|
| 661.21 | April 28, 2026 | Software update |
| 661.21 | April 2, 2026 | Software update |
| 661.21 | April 2, 2026 | Software update |
Questions buyers ask
What is TSB 661.21?
661.21 is a software update filed with NHTSA by Cadillac, Chevrolet and GMC, covering 6 Cadillac, Chevrolet and GMC models across the 2024–2025 model years. NHTSA's summary reads: • Improvements to the performance of vehicle software updates. • Fixes to help prevent loss of functionality for connectivity features, including maps and Wi-Fi. • Fixes to help prevent erroneous emergency calls from vehicle. • Fixes for deleting digital keys. • Fixes to help…
Which vehicles does 661.21 cover?
NHTSA's file names Cadillac Escalade (2025); Chevrolet Colorado (2024); Chevrolet Suburban (2025); Chevrolet Tahoe (2025); GMC Canyon (2024); GMC Yukon (2025). A bulletin number can be re-issued against more vehicles later, so check the model-year list on this page against your own.
Is TSB 661.21 a recall, and is the repair free?
661.21 is filed as a software update, not a recall — but this is the kind of communication that can mean free or reimbursed work if your VIN qualifies. Take the number to a dealer and ask. Recalls are separate and always free; check yours by VIN at nhtsa.gov/recalls.
How do I get the full text of 661.21?
Take the document ID to a dealer's service desk, or search NHTSA's manufacturer-communications records. This page carries every document ID filed under 661.21, its date, and NHTSA's own summary from the public file.
Every number on this page is a count of records in the federal complaint, recall, and investigation files published by NHTSA's Office of Defects Investigation. This page lists only what NHTSA's manufacturer-communications file records under 661.21. Check any specific vehicle's open recalls by VIN at nhtsa.gov/recalls.