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Service bulletins for the 2020 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.

156 on file from NHTSA, as of 2026-10-19.

By type

By component

Only bulletins with component: Engine are shown. Show all

Bulletins, newest first
20TS-022020-03-06. Service bulletin. ENGINE AND ENGINE COOLING. Technical Service Letter for DD Platform Heavy Duty, Metal in the Oil and Oil Filter. Some engine component failures can cause metallic debris to circulate throughout the engine lubrication system. Although the oil filter will capture most of this debris, some debris may enter the clean side of the lubrication system during oil filter bypass. Detroit has created a lubrication system cleaning and flushing procedure to address this problem.
20CSA-022020-02-01. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING. Customer Service Announcement reminding service locations to update their DiagnosticLink software. To maintain access to the Detroit server, all DiagnosticLink computers must be updated with the current version of DiagnosticLink software. all DiagnosticLink 8.08 installed versions will be disabled as of Tuesday, January 28, 2020.
20CSA-012020-02-01. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL; ENGINE AND ENGINE COOLING. Customer Service Announcement for a policy change regarding Detroit Service Information Bulletins (SIBs) will now have a 60-day expiration, starting on the release day of the bulletin. The intent of a SIB is to notify the service network of a major change to one or more service procedures. Do not save SIBs nor reference them for repairs, as they are uncontrolled and never updated.
17TS-12REV2020-01-03. Service bulletin. ELECTRICAL SYSTEM:WIRING; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Technical Service Letter for GHG17 Heavy Duty Engine Platform 1-BOX Aftertreatment System (ATS) Wire Harness experiencing chaffing caused by vibration and dirt collecting in the harness conduit.
WI19-0222020-01-02. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; ELECTRICAL SYSTEM. Warranty Information Letter announcing Detroit NOx Sensor Circuit Improvements for GHG17 After Treatment Systems
CALWS15-0012019-11-21. Service bulletin. POWER TRAIN; EQUIPMENT ADAPTIVE/MOBILITY; ENGINE. Customer Advisory Letter for Allison flex plate mounting bolts. The incorrect flex plate mounting bolts were installed for certain vehicles.
19TS-4REV2019-10-28. Service bulletin. ENGINE AND ENGINE COOLING. Technical Service Letter Revision on heavy duty coolant oil module and oil filter change. Older modules will not be compatible with newer module.
19CSA-162019-10-26. Service bulletin. ENGINE AND ENGINE COOLING. Customer Service Announcement that eParts is being retired and that PartsPro should be used instead for Detroit Engine Parts Information.
17TS92019-10-25. Service bulletin. ENGINE AND ENGINE COOLING. Technical Service Letter communicating that information on DD Heavy Duty Platform Belt and Belt Tensioner can be found on TechLit.
DOC-10345002019-10-03. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT:APPLIANCE:AIR CONDITIONER. Service Solution to fix AC cooling performance due to improper HVAC function.
19TL-152019-09-28. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING. Tool Letter for ICC5 Programming Cable
SF5912019-09-28. Service bulletin. ENGINE AND ENGINE COOLING. Field Service Campaign for Wabco HP Air Dryer Turbo Cut-off Valve

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.