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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.

Warranty extensions
CE0302026-06-25. 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."
7-7002024-11-05. POWER TRAIN; ENGINE. 7/700 Service Agreement - Letter Only.

A warranty extension may pay for a repair after the basic warranty has ended. Read the document for which vehicles and which repair it covers.

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Bulletins, newest first
42-0702026-10-17. Service bulletin. UNKNOWN OR OTHER. Due to supplier constraints, an authorized aftermarket surge tank has been made available.
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.
24KWL/PBL2026-08-20. Service bulletin. FORWARD COLLISION AVOIDANCE: WARNINGS. The verbiage in the Introduction section has been updated.
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."
43-0802026-06-17. Service bulletin. ELECTRICAL SYSTEM. "KW: A new recommended repair has been added to verify the software level and close the campaign in SIR.The repair procedure has been updated with additional note boxes for clear instructions. PB: The repair procedure has been updated with additional note boxes for clear instructions."
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.
02-1772026-06-03. Service bulletin. ELECTRICAL SYSTEM. Troubleshooting procedures for 2.1m cab power windows are now available.
43-0872026-06-03. Service bulletin. UNKNOWN OR OTHER. (KW) Certain T680 / T800 / T880 / W900 / W990 have updated GHG labels available for order and installation.
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.
14-0342026-05-06. Service bulletin. UNKNOWN OR OTHER. Bogie Crossmember Torque Value Update - Procedure has been updated to correct torque values.
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.
01-0902026-04-07. Service bulletin. UNKNOWN OR OTHER. Bulletin Update 03/02/2026 - A Meritor OnTrac case submission is required prior to repairs being completed. Failure to do so may result in warranty claim denial. See the procedure section for more details.
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.
14-0362026-04-07. Other. STRUCTURE:BODY. One-Piece Aluminum Crossmember Repair - Repair procedures are available to support the replacement of intermediate or midship one-piece aluminum crossmembers.

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