2026 Peterbilt 520 TSBs

2024-2026 PACCAR MX-11 and MX-13 engines. This bulletin will be updated when the software is ready. 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. The procedure document has also been updated for clarity.

2024-2026 PACCAR MX-11 and MX-13 engines. This bulletin will be updated when the software is ready. 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. The procedure document has also been updated for clarity.

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.

model year (EMY) 2024-2026 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.

Engine Model Year (EMY) 2026 MX-11 and MX-13 Operators Manuals.

receive proactive replacement instructions for the PM sensor to maximize uptime and maintain optimal performance.

without a check valve in the power steering system.

The engine label is now available for order and installation. PB Certain vehicle model year 2026 Peterbilt chassis equipped with EMY2025 PACCAR MX engines require an amended engine label. The engine label is now available for order and installation.

engines require a revised engine label update. (PB) Certain vehicle model year 2026 Peterbilt chassis equipped with EMY2025 PACCAR MX engines require a revised engine label update.

engines.

Control Unit (VECU) part number Q21-1157-013-011 / Q21-1157-013-013. Parts and procedures for Phase 2 chassis will be available at a later date. This bulletin will be updated at that time. Please refer to the condition section for more details. Certain Ethernet Multiplexed Architecture (EMUX) chassis fail to conform to Federal and Canada Motor Vehicle Safety Standards (FMVSS/CMVSS) No. 108. Delayed or unsteady illumination of the vehicles stop lamps, reverse lamps, turn signal lamps and inadvertent change in headlamp illumination or lift axle position may"

The total chassis count is now 53. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 8 chassis. The total chassis count is now 130. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."

The total chassis count is now 53. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 8 chassis. The total chassis count is now 130. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."

The total chassis count is now 122. KW: The chassis list has been updated to include 3 chassis. The total chassis count is now 52."

Total chassis count is now 49. PB - The chassis list has been updated to include10 chassis. The total chassis count is now 111."

display as --- after programming.

Model 520 BEV.

directs dealers to open a TCS365 case to order new labels. Warranty codes for inspection and label replacement have been updated. Certain Battery Electric Vehicles that are subject to California Air Resources Board (CARB) regulations have GHG labels that are missing the CARB Enhanced EV and FCEV Statement.

part number Q21-1157-013-011 / Q21-1157-013-013 / Q21-1157-002-002 / Q21-1157-004-004 / Q21-1157-006-006 / Q21-1157-009-009. See attached Parts Matrix for required parts per chassis.

Emissions Control Information (VECI) labels that are missing the CARB Enhanced EV and FCEV Statement.

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.

misaligned, resulting in increased stress on the steering cross shaft on the Right-Hand Stand-Up (RHSU) controls configuration. Failure of the RH steering cross shaft could result in the loss of RH steering control which may increase the risk of a crash. PB: Certain Peterbilt Model 520 / 520 BEV chassis may have Right-Hand (RH) steering cross shaft bearing mounting holes that are misaligned, resulting in increased stress on the steering cross shaft on the Right-Hand Stand-Up (RHSU) controls configuration. Failure of the RH steering cross shaft could result in the loss of RH steering control which may increase the risk of a crash.

steering shaft when turning the wheel.

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."

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.