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Service bulletins for the 2021 Western Star 4800

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.

53 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
VSWP Customer Letter2024-06-22. Other. ENGINE. Customer letter regarding variable speed water pump.
21OEM-062021-03-01. Service bulletin. ENGINE AND ENGINE COOLING. Starting on November 23, 2020, DiagnosticLink 8.13 (Build 4527) was made available. Current subscribers of DiagnosticLink 8.11 or 8.12 may upgrade to DiagnosticLink 8.13 at no cost. All DTNA Service shops & OEM locations are required to maintain the latest version of software on each of their stations.
18SP7362020-10-01. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:GASOLINE:BELTS AND ASSOCIATED PULLEYS; ENGINE AND ENGINE COOLING:COOLING SYSTEM:FAN. Detroit Diesel Special Publication informing about Heavy Duty Friction Style Belt Tensioner Kit. This heavy duty friction style belt tensioner kit contains the belt tensioner and two M10 bolts to correctly pin the friction style belt tensioner. The M10x80mm bolt is used to pin the engine cooling fan drive arm. The M10x50mm bolt is used to pin the engine accessory drive arm.
20TS-03REV22020-10-01. Service bulletin. ENGINE AND ENGINE COOLING. Revised Technical Service Letter for DD Heavy Duty Platform Belt Tensioner Change. A newly designed, dual-arm friction shoe damping tensioner was implemented for the DD Heavy Duty Platform. The revision includes additional information on retrofit and service kits.
TechTalk76792020-10-01. Service bulletin. ENGINE AND ENGINE COOLING. Tech Talk discussion on repair verification for codes like 'low air flow' when a trailer is not available.
20TS-052020-07-31. Service bulletin. ENGINE AND ENGINE COOLING. Technical Service Letter for EPA10, GHG14, GHG17 Diesel Particulate Filter (DPF) Compatibility. Note: This document supersedes 14 TS-25 and 15 TS-8. Detroit Diesel has determined that some, Diesel Particulate Filters (DPFs) are compatible in pairs and or can be mixed together within EPA10 and GHG14 Systems. For 1-BOX and Two-Box Configuration Aftertreatment Systems (ATS), this is only possible when the filters are used in accordance with Tables 1 and 2 shown below. All other DPFs, NOT mentioned below, are NOT compatible.
20OEM-052020-07-31. Service bulletin. ENGINE AND ENGINE COOLING. OEM and distributor announcement for DiagnosticLink 8.12 (Build 4527) was made available. All DTNA Service shops & OEM locations are required to maintain the latest version of software on each of their stations.
20CSA-102020-07-31. Service bulletin. ENGINE AND ENGINE COOLING. Customer Service Announcement informing that Service Pack (SP) 1 for DiagnosticLinkî 8.12 Standard and Professional is available to download from the Detroit Diesel server.
TS10330142020-07-31. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; FUEL SYSTEM, GASOLINE:DELIVERY:FUEL PUMP; ENGINE AND ENGINE COOLING. Training Solutions for Fuel Leak Found at High Pressure Fuel Pump Weep Hole for Heavy Duty DD Engines. Occasionally we see trucks come in with fuel leaking from the high pressure fuel pump weep hole. This is NOT a defect in the pump and further diagnostics need to be performed to find the root cause.
20CSA-092020-07-28. Service bulletin. ENGINE AND ENGINE COOLING. Customer Service Announcement for DiagnosticLink Software Update Reminder. Due to various software changes and fixes, vehicles will require DiagnosticLink 8.12 to perform functional programming. Failure to use this version may cause errors, incomplete programming, and poor vehicle performance. Because of this, all DiagnosticLink 8.09 installed versions will be disabled as of Thursday, July 23, 2020.
20CSA-082020-06-26. Service bulletin. ENGINE AND ENGINE COOLING. Customer Service Announcement for Release of DiagnosticLink 8.12. On Wednesday, June 10, 2020, DiagnosticLink 8.12 will be made available for download from the ordering system. Current subscribers of DiagnosticLink 8.xx can upgrade to DiagnosticLink 8.12 at no cost. All DTNA service shops are required to maintain the latest version of software on each of their stations.
20TS-03REV2020-06-26. Service bulletin. ENGINE AND ENGINE COOLING. Revised Technical Service Letter for DD Heavy Duty Platform Belt Tensioner Change. A newly designed, dual-arm friction shoe damping tensioner was implemented for the DD Heavy Duty Platform.
WI20-0092020-06-13. Service bulletin. ENGINE AND ENGINE COOLING. Warranty Information Letter for a Warranty Service Replacement Engine Program Clarification. Detroit established the Warranty Service Replacement Engine Program to support an unrepairable catastrophic engine failure due to manufacturing defect. To improve understanding and utilization of the program, DTNA is clarifying eligibility and engine returns.
WI20-0042020-04-23. Service bulletin. EQUIPMENT; ENGINE AND ENGINE COOLING. Warranty Information Letter for Warranty Long Block Program Change. The Detroit Reman Long Block Program has expanded. The expansion reduces complexity in ordering reman engines and promotes stocking reman engines to meet uptime commitments.
20CSA-042020-03-22. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT. Customer Service Announcement saying that Service Pack (SP) 3 for DiagnosticLink® 8.11 Standard and Professional will be available for download from the Detroit Diesel server.
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.

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