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Service bulletins for the 2021 Peterbilt 579

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

117 on file from NHTSA, as of 2026-10-19.

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Only bulletins with component: Engine are shown. Show all

Bulletins, newest first
P0012026-09-29. Service bulletin. ENGINE. "Kenworth: Dealers should check the chassis list and SIR weekly for VIN changes. 2 chassis added to the chassis list. Peterbilt: Dealers should check the chassis list and SIR weekly for VIN changes. 10 chassis added to the chassis list."
E3432026-09-23. Service bulletin. ENGINE. An exhaust manifold slip joint seal kit is now available for EPA 2017-2024 PACCAR MX-13 engines.
43-0882026-08-20. Service bulletin. ENGINE. The procedure has been updated to include additional steps for verifying the software level on the vehicle electronic control unit (VECU2) and digital display (DD). Steps have also been added to the PACCAR Common Rail Injection 2 (PCI2) software verification.
E3162026-08-01. Service bulletin. ENGINE. 235 chassis have been removed from the chassis list and unflagged in PRWS due to expiration of applicable warranty coverage. 5 chassis have been added to the chassis list. The total chassis population is now 15,637.
43-0882026-07-23. Service bulletin. ENGINE. This optional software update is now available for chassis equipped with EMY 2021B-2023 PACCAR MX-11 and MX-13 engines. This update provides customers with additional time to service their trucks before a DEF-related derate occurs. The software is being offered to customers in alignment with recently updated regulatory agency guidance.
41-0292026-07-22. Service bulletin. ENGINE. Incorrect air filters may be inadvertently installed in certain chassis equipped with under-hood Donaldson air filter housings.
E3162026-07-21. Service bulletin. ENGINE. The Condition, Chassis Affected, Service Action, Warranty, and Procedure sections have been updated to include the latest prognostics bulletin verbiage.
43-0882026-07-21. Service bulletin. ENGINE. "The software is not yet available. The bulletin will be updated when more information is available."
43-0882026-07-02. Service bulletin. ENGINE. "An optional software update will be available on 07/06/2026 for chassis equipped with EMY 2021B-2023PACCAR MX-11 and MX-13 engines. This update provides customers with additional time to service theirtrucks before a DEF-related derate occurs. The software is being offered to customers in alignment withrecently updated regulatory agency guidance."
CE0302026-06-25. Warranty extension. ENGINE; POWER TRAIN. "KW & PB 14 fuel injector part numbers (seven for MX-11 and seven for MX-13 engines) have been added to this warranty policy."
R21032026-06-17. Service bulletin. ELECTRICAL SYSTEM; ENGINE. Updated the point of contact for sourcing the MX Engine Overlay Harness Kits. This retrofit should have been completed by 5/15/2022 per the Action section of the bulletin. However, trucks still open in SIR are still eligible for the repairs.
41-0242026-05-20. Service bulletin. ENGINE. Procedures have been updated to include additional truck models in the service intervals table.
42-0642026-05-06. Service bulletin. ENGINE. Fix-as-Fail On certain Kenworth T680 chassis equipped with PACCAR MX-13 engines, wiring to the Horton LCX230 crank-mounted fan drive may experience a short due to chafing or water ingress, affecting fan drive operation.
45-0702026-05-06. Service bulletin. ENGINE. The attached procedures document has been updated with more detail and explanations. This is not a stand-alone procedure. Cummins Quickserve troubleshooting will specify the use of these procedures while troubleshooting specific fault codes.
E3262026-05-06. Emissions. ENGINE; ELECTRICAL SYSTEM. EPA17-24 MX Fuel Injector Connector - This bulletin has been revised to include all EPA17-24 and CARB24 PACCAR MX engines.
E3352026-04-07. Emissions. ENGINE. Expiration Date Format Update - Certain EPA21 compliant PACCAR MX-13 engines were built with intake valve springs that could fail. This failure can cause significant damage to the engine. New intake valve springs will be installed.
41-0242026-04-07. Service bulletin. ENGINE. Engine Air Filter Servicing UPDATE - Procedures are available to support the maintenance, service intervals, and intake system inspection process for all engine air intake system components.
45-0702026-02-05. Service bulletin. ENGINE. Procedure pictures updated for clarity. When troubleshooting Cummins X15 fault codes 555 or 556, follow this additional testing, inspection, and documentation procedure to help identify the root cause of dusted engines. This is not a stand-alone process but must be used alongside Cummins troubleshooting steps. Cummins Quickserve will reference this bulletin for fault codes 555 or 556.
01-0902025-12-05. Service bulletin. ENGINE. Repair procedures and warranty information for model 520EV are now available. The cab heater coolant system on Peterbilt 579EV and 520EV models may not deaerate properly, causing pump malfunctions and inadequate cab heating. Update coolant deaeration return line parts and procedures are now available to release trapped air back to the reservoir.
E3112025-09-03. Other. ENGINE; POWER TRAIN. Condition, Chassis Affected, and Warranty sections updated with the following verbiage “E311 must be flagged and open in Service Information Record (SIR) at the time of RO open date to qualify.” Also, “Through Standard Warranty or any applicable active Extended Warranty” verbiage was removed from Warranty section.
E3182025-07-02. Service bulletin. ENGINE; FUEL/PROPULSION SYSTEM. Newly designed fuel injectors are available for EPA2021 compliant PACCAR MX-series engines to optimize engine performance. Injectors must be replaced as a full set (6 injectors) and associated software must be updated at the same time.
E3272025-03-04. Emissions. ELECTRICAL SYSTEM; ENGINE. "Vehicles equipped with PACCAR MX engines with Engine Software Version NA202 or NA206 may display a dash STOP lamp incorrectly. PCI-2 software on these chassis must be reverted from NA202 to NA201 (Pack 2 injectors) or from NA206 to NA191 (Pack 1 injectors) to prevent incorrect STOP lamp display.
32-0252024-12-03. Service bulletin. ENGINE. Info Only Unnecessary starter replacements can result from customer complaints regarding engine starting issues. A new Starter Troubleshooting Guide has been created to provide a comprehensive list of starting system checks, which should reduce unnecessary starter replacements and associated warranty claims. Engine starting system warranty claims now require a completed Starter Checklist, a Battery Pack Midtronics Report, and a Cable Drop Midtronics Report. Claims filed without these documents may be denied.
7-7002024-11-05. Warranty extension. POWER TRAIN; ENGINE. 7/700 Service Agreement - Letter Only.
E3162024-09-10. Service bulletin. ENGINE. Bulletin updated to include oil pan drain plug in parts list and incorporated QR code to direct dealers to informational resources for new Programmable Torque Tool.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.