This optional software update is expected to be available in late August 2026 for chassis equipped with...

Bulletin number

43-089

Component

Engine

Summary

This optional software update is expected to be available in late August 2026 for chassis equipped with EPA 2024 EMY 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.

Owners of these vehicles have filed 1 complaints in the engine category.