Mack service campaign S4373-202502
What it saysMack Trucks has determined that certain Mack sleeper cab assemblies were possibly manufactured with an insufficient number of welds across the rear flange of the upper header. NHTSA’s full summary ↓
Mack filed this with NHTSA as a service campaign dated Feb 28, 2025, received Mar 3, 2025, about the structure. It names 2 model years (2025). A service campaign 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 communicationMack Trucks has determined that certain Mack sleeper cab assemblies were possibly manufactured with an insufficient number of welds across the rear flange of the upper header. The reduced number of welds could lower the designed cab integrity.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| S4373-202502 | Service campaign | Feb 28, 2025 | 11014712 | PDF, 632 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 themAlso filed against: 2025 Mack Anthem (an); 2025 Mack Pioneer PR (4).
None of these model years has a page on this site (it covers EPA-certified cars, trucks and SUVs from 2016), so the bulletin is listed here on its own.
More bulletins about the structure
Source: same model, same component group5 other manufacturer communications filed against these Mack models under the same component group (structure), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| S4866 032026 | Service campaign | Mar 2, 2026 | SC - Load Lock Clamp Install |
| S4808 032026 | Service campaign | Mar 2, 2026 | SC - Certain model PR’s could experience grille surround trim detaching due to insufficient retention. |
| S4373 022026 | Service campaign | Feb 26, 2026 | SC - Mack Trucks has determined that certain Mack sleeper cab assemblies were possibly manufactured with an insufficient number of welds acr… |
| S4578 072025 | Service campaign | Jul 1, 2025 | SC - Mack Trucks has determined that certain AN models were assembled without a crossmember that was needed for the pusher axle. |
| S4548 202506 | Service campaign | Jun 1, 2025 | Mack Trucks has determined that certain model year 2020 to 2022 Anthem trucks could experience excessive wear on the hood latch pins causing… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Mack, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Mack S4373-202502 a recall?
No. A service campaign 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.
Is the S4373-202502 repair free?
A service campaign 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 S4373-202502 cover?
The manufacturer filed it against 2 model years: 2025 Mack Anthem (an), 2025 Mack Pioneer PR (4). Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.