Mercedes-Benz bulletin LI54.21-P-080326
Mercedes-Benz filed this with NHTSA as a service bulletin dated Jul 24, 2026, received Mar 10, 2026, about the electrical system — 4 documents under this number. It names 53 model years (2019–2026). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationComplaint CEL light on with no drivability concerns. Cause Signal timing error. Remedy 167: SW has been released. Update the FSAM to the latest SW version. 465, 290, 118, 243, 247: Software is still in development. This fault code does not cause a drivability concern and will clear itself within 2-3 key cycles. The vehicle can be released back to the customer.
Documents filed under this number
| Document | Kind | Dated | NHTSA id |
|---|---|---|---|
| LI54.21-P-080326 | Service bulletin | Jul 24, 2026 | 11035217 |
| LI54.21-P-080326 | Service bulletin | Jul 2, 2026 | 11034506 |
| LI54.21-P-080326 | Service bulletin | Jun 22, 2026 | 11034016 |
| LI54.21-P-080326 | Service bulletin | Mar 2, 2026 | 11029925 |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5; the full text comes from the manufacturer or a dealer. 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. Quote it at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themand 7 more model years on this site.
Also filed against model years this site has no page for: 2023 Mercedes-Benz AMG GT 63 S E Coupe; 2022 Mercedes-Benz AMG GT63; 2022 Mercedes-Benz AMG GT63 S; 2024 Mercedes-Benz AMG GT63 S E; 2024 Mercedes-Benz AMG GT63 S E Performance; 2026 Mercedes-Benz AMG GT63 S E Performance 4MATIC+.
A 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 Mercedes-Benz LI54.21-P-080326 a recall?
No. A service bulletin 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 LI54.21-P-080326 repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way.
Which vehicles does LI54.21-P-080326 cover?
The manufacturer filed it against 53 model years: 2026 Mercedes-Benz AMG GT, 2025 Mercedes-Benz AMG GT, 2024 Mercedes-Benz AMG GT, 2023 Mercedes-Benz AMG GT, 2022 Mercedes-Benz AMG GT, 2021 Mercedes-Benz AMG GT and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.