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Service bulletin 05-78-20

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 id10182214
Published by NHTSA2020-11-05
Manufacturer's number05-78-20
Manufacturer's date2020-10-13
NHTSA componentELECTRICAL SYSTEM; TIRES:PRESSURE MONITORING AND REGULATING SYSTEMS

NHTSA's summary

This Service Information Bulletin announces additional diagnostic procedures for TPMS related DTC C2921 on the applicable models listed.

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, Tires, Tire pressure monitoring

Trouble codes named

C2921

Vehicles listed
SUBARU ASCENT2019, 2020, 2021
SUBARU CROSSTREK2018, 2019, 2020
SUBARU FORESTER2019, 2020, 2021
SUBARU IMPREZA2017, 2018, 2019, 2020, 2021
SUBARU LEGACY2018, 2019, 2020

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

Other bulletins for the same vehicles and component
07-129-182018-03-13. Service bulletin. This bulletin announces availability of reprogramming files to optimize operation of the Tire Pressure Monitor System?s (TPMS) real-time display function. Under certain high-altitude conditions, the tire pressure values displayed in the combination meter may not be accurate.