# Service bulletins for the 2021 Peterbilt 520

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.

57 bulletins from NHTSA, as of 2026-10-19.

- [42\-070](/bulletins/11038569.md), 2026-10-17, Service bulletin: UNKNOWN OR OTHER. Due to supplier constraints, an authorized aftermarket surge tank has been made available.
- [P001](/bulletins/11037541.md), 2026-09-29, 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."
- [24KWL/PBL](/bulletins/11036291.md), 2026-08-20, Service bulletin: FORWARD COLLISION AVOIDANCE: WARNINGS. The verbiage in the Introduction section has been updated.
- [43\-088](/bulletins/11036289.md), 2026-08-20, 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.
- [43\-088](/bulletins/11035202.md), 2026-07-23, 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.
- [E318](/bulletins/11035147.md), 2026-07-22, Service bulletin: ENGINE. The Condition, Chassis Affected, Service Action, Warranty, and Procedure sections have been updated to include the latest prognostics bulletin verbiage. The Warranty section has also been updated to include Peterbilt specific SRT codes for filing cross\-division repairs.
- [43\-088](/bulletins/11035108.md), 2026-07-21, Service bulletin: ENGINE. "The software is not yet available. The bulletin will be updated when more information is available."
- [25KWD 25PBD](/bulletins/11035096.md), 2026-07-20, Service campaign: ELECTRICAL SYSTEM; FUEL/PROPULSION SYSTEM. Additional US chassis have been added, along with additional Canadian chassis under identical safety recall 26PACB.
- [43\-088](/bulletins/11034394.md), 2026-07-02, 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."
- [CE030](/bulletins/11034057.md), 2026-06-25, 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\-080](/bulletins/11033918.md), 2026-06-17, 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."
- [R2103](/bulletins/11033914.md), 2026-06-17, 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.
- [46\-028](/bulletins/11033352.md), 2026-06-03, Service campaign: STEERING. Certain Peterbilt Model 520 BEV chassis with an Accelera Power Control and Accessory System \(PCAS\) were manufactured without a check valve in the power steering system.
- [E326](/bulletins/11032284.md), 2026-05-06, 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.
- [46\-019](/bulletins/11026418.md), 2025-12-05, Service bulletin: UNKNOWN OR OTHER. Repair procedures and warranty information for model 520EV are now available. Certain Peterbilt 579EV and 520EV chassis have the First Responder Guide \(FRG\) label incorrectly showing the cut loop on the wrong side and are missing the Low Voltage Battery Disconnect Switch and Do Not Jump Start labels. These labels are now available for installation.
- [01\-090](/bulletins/11026416.md), 2025-12-05, 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.
- [E318](/bulletins/11020043.md), 2025-07-02, 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.
- [98\-030](/bulletins/11019172.md), 2025-06-05, Service bulletin: ELECTRICAL SYSTEM. 5/29/2025: A new Ethernet Multiplexed Architecture \(EMUX\) Service Tool Kit service manual \(SM034\-022\) has been released to provide general use information. The new EMUX Service Tool Kit improves cab \& chassis electrical troubleshooting efficiency, while reducing risk of component damage. 4/29/2025: The Ethernet Multiplexed Architecture \(EMUX\) Service Tool Kit and individual kit components are now available to order. Dealers that have received their first kit may order an additional kit. The EMUX Service Tool Kit Part number has been updated to match OEM drawings \(P74\-1045\-001\). Individual kit component part numbers can be found in the Reference Bill of Materials sheet. The new EMUX Service Tool Kit improves cab \& chassis electrical troubleshooting efficiency, while reducing risk of component damage. Information Only New diagnostic tool is required to support PACCAR Ethernet Multiplexed Architecture \(EMUX\). The EMUX Service Tool Kit will help improve cab \& chassis electrical troubleshooting efficiency, while reducing the risk of component damage.
- [46\-016](/bulletins/11017898.md), 2025-05-06, Service campaign: ELECTRICAL SYSTEM. 4/29/2025: Campaign A software update is available for 520EV and 579EV Battery Electric Vehicles. This software update corrects or improves certain functions. Software update procedures have been revised. Campaign start date is 12/05/2024. Campaign A software update is available for 520EV and 579EV Battery Electric Vehicles. This software update corrects or improves certain functions. Campaign start date is 12/05/2024.
- [43\-080 PB](/bulletins/11016473.md), 2025-04-04, Service campaign: ELECTRICAL SYSTEM. As of 03/25/2025, this campaign has resumed. Software updates are now available to complete this campaign.
- [E327](/bulletins/11014768.md), 2025-03-04, 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.
- [46\-013](/bulletins/11014754.md), 2025-03-04, Service campaign: ELECTRICAL SYSTEM. Certain Peterbilt 579EV and 520EV Battery Electric Vehicles were built prior to the availability of certain labels and Low Voltage Distribution System \(LVDS\) Components. Affected chassis will be inspected and necessary components will be installed.
- [24PBL](/bulletins/11013775.md), 2025-02-05, Service bulletin: FORWARD COLLISION AVOIDANCE: WARNINGS; UNKNOWN OR OTHER; ELECTRICAL SYSTEM. Safety Recall Updated software and procedures are now available. Certain Vehicle Model Year 2021\-2025 Peterbilt chassis configured for trailer towing require a software update for the Bendix EC80 ABS ECU. Software update procedures for certain Battery\-Electric Vehicles \(BEV\) and EC80 ABS ECU part numbers are not yet available. This bulletin will be updated when software update procedures are available for these chassis. Safety Recall publish date: 1/10/25
- [32\-025](/bulletins/11010926.md), 2024-12-03, 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.
- [46\-011](/bulletins/11010890.md), 2024-12-02, Service bulletin: ELECTRICAL SYSTEM; POWER TRAIN. Some 579EV and 520EV BEV trucks may have loose or improperly torqued ESS gland nuts. This may cause an intermittent warning light on the dash display.

More: [the next page](/v1/vehicles/2021_peterbilt_520/bulletins?cursor=2024-12-02_11010890) (JSON)

JSON: [/v1/vehicles/2021_peterbilt_520/bulletins](/v1/vehicles/2021_peterbilt_520/bulletins)

[Report an error on this page](https://github.com/wenmar-pro/wenmar-open/issues/new?template=data_correction.yml&title=Data%20correction%3A%202021%20Peterbilt%20520&page=https%3A%2F%2Fopen.wenmarpro.com%2Fmakes%2Fpeterbilt%2F520%2F2021%2Fbulletins&vehicle=2021%20Peterbilt%20520)