# Service bulletin 43\-088

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.

- Type: Service bulletin
- NHTSA id: 11035202
- Published by NHTSA: 2026\-07\-23
- Manufacturer's number: 43\-088
- Manufacturer's date: 2026\-07\-21
- NHTSA component: ENGINE

## NHTSA's summary

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.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2026/MC-11035202-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2026/MC-11035202-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine

## Vehicles listed

- 2024 to 2025 KENWORTH L770
- 2020 to 2025 KENWORTH T680
- 2020 to 2025 KENWORTH T880
- 2020 to 2021 KENWORTH T880B
- 2020 to 2025 KENWORTH W990
- 2020 to 2025 PETERBILT 365
- 2020 to 2025 PETERBILT 367
- 2020 to 2025 PETERBILT 389
- 2020 to 2025 PETERBILT 520
- 2020 to 2025 PETERBILT 567
- 2020 to 2025 PETERBILT 579

## Recalls for the same vehicles and component

- [23V749000](/recalls/nhtsa/23V749000.md), 2023-11-07: ENGINE
- [2022470](/recalls/tc/2022470.md), 2022-08-18: Engine
- [22V631000](/recalls/nhtsa/22V631000.md), 2022-08-17: ENGINE AND ENGINE COOLING:ENGINE:ENGINE CONTROL MODULE \(ECU/ECM\)
- [21V080000](/recalls/nhtsa/21V080000.md), 2021-02-17: ENGINE
- [19V282000](/recalls/nhtsa/19V282000.md), 2019-04-09: ENGINE; ELECTRICAL SYSTEM

## Other bulletins for the same vehicles and component

- [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."
- [E343](/bulletins/11037451.md), 2026-09-23, Service bulletin: ENGINE. An exhaust manifold slip joint seal kit is now available for EPA 2017\-2024 PACCAR MX\-13 engines.
- [P003](/bulletins/11037450.md), 2026-09-23, Service bulletin: ENGINE. "KW: A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 1 chassis. The total chassis count is now 10. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."
- [P001](/bulletins/11037449.md), 2026-09-23, Service bulletin: ENGINE. "KW: The chassis list has been updated to include 1 chassis. 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."
- [P002](/bulletins/11037448.md), 2026-09-23, Service bulletin: ENGINE. "KW: A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 2 chassis. The total chassis count is now 4. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."
- [P003](/bulletins/11036428.md), 2026-08-27, Service bulletin: ENGINE. "KW: A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 1 chassis. The total chassis count is now 10. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."
- [P002](/bulletins/11036427.md), 2026-08-27, Service bulletin: ENGINE. "KW: A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section. PB: The chassis list has been updated to include 2 chassis. The total chassis count is now 4. A link to the PACCAR Powertrain Prognostics Webcast has been added in the Links section."
- [P001](/bulletins/11036426.md), 2026-08-27, Service bulletin: ENGINE. "KW: The chassis list has been updated to include 1 chassis. 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."
- [43\-089](/bulletins/11036342.md), 2026-08-25, Service bulletin: ENGINE. This optional software update is expected to be available after 08/28/2026.
- [P003](/bulletins/11036340.md), 2026-08-25, Service bulletin: ELECTRICAL SYSTEM; ENGINE. The PB chassis list has been updated to include 1 chassis. The total chassis count is now 9.

JSON: [/v1/bulletins/11035202](/v1/bulletins/11035202)

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