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Service bulletin M1720

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 id11031172
Published by NHTSA2026-04-08
Manufacturer's numberM1720
Manufacturer's date2026-03-31
NHTSA componentELECTRICAL SYSTEM; POWER TRAIN; ENGINE; VEHICLE SPEED CONTROL; FUEL/PROPULSION SYSTEM

NHTSA's summary

SERVICE BULLETIN M1720 (REV A): PAN AMERICA ELECTRONIC CONTROL MODULE (ECM) UPDATE. PURPOSE: Initial release 3/3/2026. Revision A. 3/30/2026. Updated: Purpose for Service Bulletin and Required Dealer Action. Adjust information for 2024 models. Purpose for Service Bulletin. This bulletin informs dealers that there is an Electronic Control Module (ECM) update available for 2021-2025 RA1250, RA1250S, RA1250ST and RA1250SE on Digital Technician II (DT II). The update improves engine function by addressing engine operation after a cold start by improving idle stability and improved Quickshifter function. For 2021-2024 models the Body Control Module (BCM) and ECM update must both be completed. If only the ECM is updated, a nuisance Diagnostic Trouble Code (DTC) U040000 will populate and not be able to be cleared. Because of this, the BCM update should be done first and then the ECM.

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

Electrical system, Engine, Fuel system, Throttle and cruise control, Transmission and driveline

Trouble codes named

U0400

Vehicles listed
HARLEY-DAVIDSON RA12502021 to 2024
HARLEY-DAVIDSON RA1250S2021 to 2025
HARLEY-DAVIDSON RA1250SE2024 to 2025
HARLEY-DAVIDSON RA1250ST2025

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