Service bulletins for the 2021 Western Star 4900
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.
117 on file from NHTSA, as of 2026-10-19.
By type
By component
Only bulletins with component: Mirrors are shown. Show all
| SS1034711 | 2020-05-23. Service bulletin. VISIBILITY:REARVIEW MIRRORS/DEVICES. Service Solution for Hadley Upper Mirror Glass Vibration. The following suggestions are not guaranteed to eliminate or fix the Hadley mirror vibration concern. We have had mixed results in field-testing. In some cases, these solutions eliminate or reduce the vibration and in others, it does not seem to make a difference. DTNA continues to work on a permanent solution to this concern. |
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The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.