Mack service campaign S4757 022026
What it saysSC - Certain model AN(4)’s and PR’s could experience DEF leaks or crystallization due to the installation of incorrect fasteners for the Urea Dosage Valve. NHTSA’s full summary ↓
Mack filed this with NHTSA as a service campaign dated Feb 1, 2026, received Mar 3, 2026, about the engine. It names 3 model years (2025–2026). 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 communicationSC - Certain model AN(4)’s and PR’s could experience DEF leaks or crystallization due to the installation of incorrect fasteners for the Urea Dosage Valve.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| S4757 022026 | Service campaign | Feb 1, 2026 | 11029456 | PDF, 345 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: 2026 Mack Anthem AN (4); 2025 Mack Pioneer PR (4); 2026 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 engine
Source: same model, same component group1 other manufacturer communication filed against these Mack models under the same component group (engine), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| SC S4742 202601 | Service campaign | Jan 2, 2026 | CBR MCO/VECI Label Reprint. |
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 S4757 022026 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 S4757 022026 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 S4757 022026 cover?
The manufacturer filed it against 3 model years: 2026 Mack Anthem AN (4), 2025 Mack Pioneer PR (4), 2026 Mack Pioneer PR (4). Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.