Kenworth L770 2024–2026 — technical service bulletin
Bulletin 43-089 · NHTSA communication 11035433 · issued Aug 1, 2026
Technical service bulletin
communication type
Engine
component
2024–2026
model years
28
vehicle entries
Official summary
This optional software update is expected to be available on 08/07/26 for chassis equipped with EPA 2024 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.
Vehicles covered
- 2024 Kenworth L770
- 2025 Kenworth L770
- 2026 Kenworth L770
- 2024 Kenworth T680
- 2025 Kenworth T680
- 2026 Kenworth T680
- 2024 Kenworth T880
- 2025 Kenworth T880
- 2026 Kenworth T880
- 2024 Kenworth W900
- 2025 Kenworth W900
- 2024 Kenworth W900B
- 2025 Kenworth W900B
- 2024 Kenworth W990
- 2025 Kenworth W990
- 2026 Kenworth W990
- 2024 Peterbilt 520
- 2025 Peterbilt 520
- 2026 Peterbilt 520
- 2024 Peterbilt 567
- 2025 Peterbilt 567
- 2026 Peterbilt 567
- 2024 Peterbilt 579
- 2025 Peterbilt 579
- 2026 Peterbilt 579
- 2024 Peterbilt 589
- 2025 Peterbilt 589
- 2026 Peterbilt 589
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.