WenmarOpen by Wenmar Pro

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: Equipment and accessories are shown. Show all

Bulletins, newest first
WSTCAE180-20202021-05-18. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. Portland Truck Plant Paint Changes
WI21-0082021-04-23. Service bulletin. EQUIPMENT. Warranty Information Letter announcing DTNA is adjusting the Standard Repair Times (SRTs) shown. The updated times will be applied to repair orders opened on or after April 5, 2021.
DT12 Trans Chafe2021-04-08. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; POWER TRAIN. DTNA received a field notification on multiple units regarding diagnostic fault codes that were found to be causing issues to the After Treatment Control Module (ACM). These fault codes indicated that the ACM communication message was not received by the Motor Control Module (MCM) which in certain cases, led to a 25% engine de-rate situation. Further diagnosis revealed that the DT12 wiring harness was chafing and contacting the transmission TCU case. To reduce potential chafing areas, the proposed short-term containment was to route the wiring harness using additional tie straps. This communication applies to Freightliner and Western Star vehicles built with DT12 transmissions.
WP60-1002021-03-25. Service bulletin. EQUIPMENT. Updated Western Star Parts Technical Bulletin for Universal Design Floor Mats. This bulletin replaces the version dated February 12, 2021. Information about parts notes in the Paragon system have been added and the trimming instructions are revised. Universal floor mat designs fit multiple cab configurations and may require trimming. Trim lines displaying size options are scored into the pad side of the mat; use an existing floor mat as a guide for optimal results. The new mat should not interfere with safety-critical equipment, such as foot pedals.
SBW54-0572021-03-25. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Western Star Service Bulletin for Powernet Troubleshooting Guide - Batteries, Path, Alternator, and Starter. When troubleshooting powernet issues, use the BCT-460DTNA PowerNet Assessment Tool. As of May 29, 2018, the AutoMeter is the only Daimler-approved tool for troubleshooting vehicle Powernet issues.
WP21-0072021-03-24. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Warranty Policy Letter for battery tags. DTNA determined that since adopting the AutoMeter BCT-460DTNA Powernet Assessment Tool (AutoMeter) as the required powernet system tester, not all battery tags have to be retained support Warranty-related claims.
WP60-1002021-02-27. Service bulletin. EQUIPMENT. Western Star Parts Technical Bulletin for Universal Design Floor Mats. Universal floor mat designs fit multiple cab configurations and may require trimming. Trim lines displaying size options are scored into the pad side of the mat; use an existing floor mat as a guide for optimal results. The new mat should not interfere with safety-critical equipment, such as foot pedals.
ICI21-0032021-02-26. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Superseding Letter to an Important Campaign Information Letter to announce a reimbursement available to dealers for travel to a customer's location to perform a recall or field service campaign. Potential travel reimbursement applies to DTNA truck dealers and Detroit Diesel distributors. Thomas Built Buses will be addressed separately. This letter supersedes ICI20-022R.
WI21-0062021-02-26. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Warranty Information Letter for Detroit NOx Sensor Circuit Fault Codes - Claim Guidelines.
WI21-0052021-02-25. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL; EQUIPMENT. Warranty Information Letter for Body Builder/Truck Equipment Manufacturer Demonstration Program.
WI20-014R2021-02-25. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Revised Warranty Information Letter for OWL and Warranty Manual Improvement: Sublets and Travel Time/Distance. In the spirit of continuous improvement, DTNA reviewed sublet-related policies and procedures. The goal was to improve language clarity and optimize processes. Revisions are in blue font.
21TS-012021-01-28. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING. Technical Service Letter for Detroit Bearing Failures - Standard Diagnostic Times. DTNA is increasing repair strategies for determining the root cause of Detroit DD heavy duty lower end bearing failures. To support this strategy change, Detroit now has two (2) Standard Diagnostic Times (SDTs), easy and difficult, which can be applied to repair orders.
WI21-0032021-01-28. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY. Warranty Information Letter for Detroit Bearing Failures - Standard Diagnostic Times. DTNA is increasing repair strategies for determining the root cause of Detroit DD heavy duty lower end bearing failures. To support this strategy change, Detroit now has two (2) Standard Diagnostic Times (SDTs), easy and difficult, which can be applied to repair orders.
SBW42-0142020-12-22. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; SERVICE BRAKES; EQUIPMENT. Western Star Service Bulletin for Access to Front Brake Zerk Fittings. Certain vehicles with Detroit front axles and Meritor EX-L front air disc brakes do not have access to the front brake zerk fittings for lubrication.
WP20-0182020-12-12. Service bulletin. STEERING; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; POWER TRAIN. Warranty Policy Letter for Alliance/Mascot Aftermarket Warranty and Claim Filing. With Mascot now in partnership with Detroit Reman and Alliance Parts, DTNA is pleased to announce that Mascot coverage has been added to OWL. Remanufactured Alliance/Mascot parts include transmission, differential, steering gear, and steering pump used in an on-highway vehicle applications. The Alliance/Mascot aftermarket warranty coverage period has not changed: depending on the part, coverage is for one (1) or two (2) years and current parts, labor, and reimbursement policies apply.
18SP7442020-12-08. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ENGINE AND ENGINE COOLING; FUEL SYSTEM, GASOLINE:FUEL INJECTION SYSTEM:FUEL RAIL. Special Publication letter for Two-Filter Fuel System KM59 GEN1 DD15 DD16 Severe Duty High Pressure Fuel Rail Feed Lines Service Kit.
TechTalk77742020-11-03. Service bulletin. VISIBILITY; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Tech Talk discussion on SS 1034711 HADLEY MIRROR
20TS-062020-10-13. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ENGINE AND ENGINE COOLING. DDC Technical Service Letter for GHG17 DD Platform Heavy Duty Oil Pan Drain Plug Inserts. Some GHG17 DD Platform Heavy Duty oil pans may experience an issue with the oil pan drain plug insert spinning during removal or installation while completing an oil change. Leaking may also be observed at the drain plug and/or other plugs in the oil pan.
SBW54-0762020-10-12. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Western Star Service Bulletin for Connecting the Chassis Harness Connector to the Cab Front Wall 104-Way Pass-Through Connector. This bulletin describes how the chassis harness connector functions and how to verify the four locks of the terminal stabilizer plate on the 104-way pass-through connector are in pre-stage position. The terminal stabilizer plate is the white plastic plate located inside the 104-way pass-through connector. The stabilizer plate floats up and down in the pass-through connector to protect the terminals from being damaged when the chassis harness connector is removed and connected.
TechTalk47252020-09-30. Service bulletin. STEERING; EQUIPMENT. Tech Talk discussion about power steering fluid.
20CSA-152020-09-02. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING; EQUIPMENT. Customer Service Announcement for Release of DiagnosticLink 8.12 Service Pack 2. On Thursday, September 3, 2020, Service Pack (SP) 2 for DiagnosticLink 8.12 Standard and Professional will be made available to download from the Detroit Diesel server.
CALWST46-0022020-09-01. Service bulletin. STEERING; EQUIPMENT. Customer Advisory Letter for Torque Validation of Steering Wheel Mounting Bracket Bolts. Western Star 4700 & 4900 vehicles equipped with a certain steering wheel mounting bracket bolt installation may have a low toque value setting.
ICI20-0262020-09-01. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Important Campaign Information Letter informing that revised bulletins for Detroit Diesel campaigns D20R1REV1 and D20M8REV1 have been posted on DTNAConnect.
ICI20-022R2020-08-29. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Revised letter is to announce a reimbursement available to dealers for travel to a customer's location to perform a recall or field service campaign. Potential travel reimbursement applies to DTNA truck dealers and Detroit Diesel distributors. Thomas Built Buses will be addressed separately.
CALWST46-0022020-08-08. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT; STEERING. Customer Advisory Letter for Torque Validation of Steering Wheel Mounting Bracket Bolts. Western Star 4700 & 4900 vehicles equipped with a certain steering wheel mounting bracket bolt installation may have a low toque value setting.

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