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Service bulletin 26-AT-004H TSB

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 id11033839
Published by NHTSA2026-06-16
Manufacturer's number26-AT-004H TSB
Manufacturer's date2026-06-05
NHTSA componentPOWER TRAIN

NHTSA's summary

This bulletin provides information related to a Transmission Control Unit (TCU) software update for some vehicles equipped with an 8-speed wet dual clutch transmission (8WDCT). The software update revises the touch point learning variation, improving drivability and judder symptoms. Certain 8WDCTs (indicated by a new part number) received an updated clutch spring. The correct TCU software update must be matched with the correct corresponding 8WDCT hardware, otherwise, drivability concerns may occur. This service procedure should be performed prior to any 8WDCT replacements done for drivability/judder concerns.

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

Transmission and driveline

Vehicles listed
HYUNDAI ELANTRA N2022, 2023, 2024, 2025, 2026
HYUNDAI KONA N2022, 2023
HYUNDAI VELOSTER N2021, 2022

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

Recalls for the same vehicles and component
22V7460002022-10-06. POWER TRAIN:AUTOMATIC TRANSMISSION

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
23-AT-002H2023-06-02. Service bulletin. This bulletin provides service procedures to prevent possible moisture intrusion of the HP EOP (High Flow Electric Oil Pump) connector when servicing the 8-speed wet dual clutch transmission (8WDCT). If moisture enters the HF EOP connector, this can result in corrosion and insufficient connection of the terminals.
22-AT-011H2022-11-01. Service bulletin. This bulletin outlines changes to the service manual regarding the replacement of 8-speed dual clutch transmissions (DCT) and associated transmission control module (TCM). Additional steps, not in the service manual, are required within GDS prior to replacing the DCT/TCM, otherwise drivability concerns and/or DTCs may occur.