Service bulletin 20-21

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.

The communication, as NHTSA indexes it (as of 2026-10-19)
Type	Service bulletin
NHTSA id	10124154
Published by NHTSA	2017-11-17
Manufacturer's number	20-21
Manufacturer's date	2014-08-01
NHTSA component	ENGINE

NHTSA's summary

20-21 - Fan Shroud Fastener Retrofit, 4700 with DD13 Engine

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Vehicles listed
WESTERN STAR 4700	2011, 2012, 2013

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
12V074000	2012-02-28. ENGINE AND ENGINE COOLING:ENGINE:DIESEL

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
16TS-08REV	2021-04-24. Service bulletin. Detroit Technical Service Letter for DD13 Cylinder Head and Cylinder Head Gasket Change.
WI21-009	2021-04-24. Service bulletin. Warranty Information letter announcing that DTNA is increasing the Standard Diagnostic Times (SDTs) shown. The updated after treatment system (ATS) diesel exhaust fluid (DEF) pump times will be applied to repair orders opened on or after April 12, 2021.
D21M2	2021-03-02. Service bulletin. DDC Field Service Campaign for GHG14 DETROIT DD13 with One-Box Aftertreatment Software Reprogramming. Certain Detroit Model Year 2013 to 2015 GHG14 DD13 engines that are registered in California will require reprogramming to a minimum of the MCM software version and fuel map version listed below: MCM Software Version 4.7.0.0 ZGS 005.
TechTalk7679	2020-10-01. Service bulletin. Tech Talk discussion on repair verification for codes like 'low air flow' when a trailer is not available.
20CSA-15	2020-09-02. Service bulletin. 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.
20TS-05	2020-07-31. Service bulletin. 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.
TS1033014	2020-07-31. Service bulletin. 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.
D20M1	2020-04-24. Service bulletin. Updated DDC Field Service Campaign for GHG14 DETROIT DD13 with Two-Box Aftertreatment Software Reprogramming. Certain Detroit Model Year 2013 to 2015 GHG14 DD13 engines that are registered in California will require reprogramming to a minimum of the MCM software version and fuel map version listed below: MCM Software Version 4.7.0.0 ZGS 005. Certain sections have been updated for clarity.
WI20-004	2020-04-23. Service bulletin. 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.
20TS-01	2020-01-22. Service bulletin. Technical Service Letter for DDC Series 60 engines concerning Series 60 Cylinder Head Resurfacing/Finish. Detroit Diesel does not recommend third party resurfacing of Series 60 cylinder heads (outside of Detroit and Detroit Reman).