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Service bulletin D20M2

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)
TypeService bulletin
NHTSA id10182137
Published by NHTSA2020-11-04
Manufacturer's numberD20M2
Manufacturer's date2020-10-29
NHTSA componentPOWER TRAIN; EQUIPMENT; ENGINE AND ENGINE COOLING

NHTSA's summary

Detroit Diesel Field Service Campaign for DETROIT TM2020 Transmission Replacement. It has been discovered that certain TM2020 units have porosity issues in and around the oil cooler line fittings on the center housing.

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, Equipment and accessories, Transmission and driveline

Vehicles listed
FREIGHTLINER CASCADIA2020
WESTERN STAR 57002020

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

Recalls for the same vehicles and component
22V3380002022-05-16. EQUIPMENT:OTHER:LABELS
19V1370002019-02-27. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; POWER TRAIN:AUTOMATIC TRANSMISSION:GEAR POSITION INDICATION (PRNDL)

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
TSB-26-057-FTL2026-06-01. Service bulletin. Revised Technical Service Bulletin for DT12 OVX Transmission Refresh
TSB-26-055-FTL2026-02-03. Service bulletin. Revised Technical Service Bulletin for DT12 Excessive Wear
TSB-26-055-FTL2026-02-03. Service bulletin. Technical Service Bulletin for DT12 Excessive Wear
TSB-26-052-FTL2026-02-03. Service bulletin. Technical Service Bulletin for DT12 PTO Upfit
FleetCom_Passive Lube2026-01-08. Other. Fleet Communications for Detroit Axle NFD ALM to Passive Lube Management
FleetCom_Oil Plug Loc2026-01-08. Other. Fleet Communications for NFD Lower Oil Plug Location - SP Axles
FleetCom_NFD Axle2026-01-08. Other. Fleet Communications for Detroit NFD Axle - Factory Fluid Change
FleetCom_Heater Core2026-01-08. Other. Fleet Communications for Heater Core Plugging
FleetCom_SS 3163-FTL2025-12-06. Other. Fleet Communications for Power Steering Reservoir Fill Cap Venting
FleetCom_Low Coolant2025-12-05. Other. Fleet Communications for Low Coolant Sensor