TSB 662.21 — Chevrolet and GMC Software update
662.21 is a software update on file with NHTSA for 5 Chevrolet and GMC models, 2026 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. This update contains a required software change to help improve the overall software update and diagnostics process. Be sure to install this update to be able to receive future software updates. During the update process, your radio may stay on up to 5 minutes after you exit the…
NHTSA's own summary of the document, quoted from the public manufacturer-communications file.
Worth checking your VIN against. 662.21 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 662.21 names
| Vehicle | Model years |
|---|---|
| Chevrolet Colorado | 2026 |
| Chevrolet Silverado 1500 | 2026 |
| Chevrolet Silverado 2500 | 2026 |
| GMC Canyon | 2026 |
| GMC Sierra 1500 | 2026 |
Every document filed under 662.21
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 |
|---|---|---|
| 662.21 | July 30, 2026 | Software update |
| 662.21 | July 15, 2026 | Software update |
| 662.21 | July 14, 2026 | Software update |
Questions buyers ask
What is TSB 662.21?
662.21 is a software update filed with NHTSA by Chevrolet and GMC, covering 5 Chevrolet and GMC models across the 2026 model years. NHTSA's summary reads: This update contains a required software change to help improve the overall software update and diagnostics process. Be sure to install this update to be able to receive future software updates. During the update process, your radio may stay on up to 5 minutes after you exit the…
Which vehicles does 662.21 cover?
NHTSA's file names Chevrolet Colorado (2026); Chevrolet Silverado 1500 (2026); Chevrolet Silverado 2500 (2026); GMC Canyon (2026); GMC Sierra 1500 (2026). 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 662.21 a recall, and is the repair free?
662.21 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 662.21?
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 662.21, 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 662.21. Check any specific vehicle's open recalls by VIN at nhtsa.gov/recalls.