Service bulletins for the 2018 Peterbilt 520
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.
49 on file from NHTSA, as of 2026-10-19.
About P1644 on the 2018 Peterbilt 520: what the code means, and the bulletins and recalls about the same components.
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Only bulletins with trouble code: P1644 are shown. Show all
| 34-074 | 2019-05-13. Service bulletin. ELECTRICAL SYSTEM. Non Safety Campaign: Vehicles were built with a 5 bolt supply wire for the air dryer pressure sensor that is no longer required with current architecture. If left in place, a fault code P1644 may be set. |
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The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.