Hyundai bulletin 26-AT-004H
What it saysThis 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). NHTSA’s full summary ↓
Hyundai filed this with NHTSA as a service bulletin dated Jun 5, 2026, received Jun 16, 2026, about the power train — 1 document under this number: 26-AT-004H TSB. It names 9 model years (2021–2026). A service bulletin is not a safety recall: it is the manufacturer telling its dealers how to diagnose or repair a condition, and whether the work is paid for depends on the warranty in force. Quoting the number at a service desk can save a diagnosis.
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What the bulletin says
Source: NHTSA's summary of the manufacturer's communicationWhat it applies to, as NHTSA’s summary states it — build dates and equipment as the manufacturer filed them. The dealer checks the VIN and the build date on the door jamb; a vehicle outside the window is not covered by this bulletin.
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.
Document filed under this number
| Document | Kind | Dated | NHTSA id | At NHTSA |
|---|---|---|---|---|
| 26-AT-004H TSB | Service bulletin | Jun 5, 2026 | 11033839 | PDF, 625 KB |
The summary is NHTSA’s abstract of the document, as filed under 49 CFR 579.5. One communication is usually filed as several documents — the bulletin, a dealer notice, an owner letter — and the number on any of them finds this page. A PDF link is shown only once NHTSA’s own server has been seen to serve that document; the rest are checked over the following nights. Quote the number at a service desk; it is what the dealer’s system is keyed on.
Model years it names
Source: as the manufacturer filed themA vehicle page’s bulletin list shows the newest few communications filed against that model year; the count there is every one.
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What owners reported
Source: NHTSA complaint databaseOwners of the 9 model years this bulletin names have filed 702 complaints with NHTSA since 2015. 59 of them name Power Train — the same broad component group this bulletin is filed under. NHTSA groups complaints coarsely, so that means the same area of the vehicle, not necessarily the same fault.
The contact owns a 2021 Hyundai Veloster N. The contact received notification of NHTSA Campaign Number: 22V746000 (Power Train) however, the part to do the recall repair was not yet available. The local dealer was contacted. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair.
2021 Hyundai Veloster · Power Train · filed with NHTSA Dec 13, 2022 · ODI 11497291
Complete and sudden clutch failure and unable to shift into any gear. No clutch slippage or change in engage point/clutch burning smell. Was traveling at relatively low speed (35mph). Dealership tried to get me to tell my insurance company it was due to water damage and then quoted me almost $7,000 to replace the clutch
2022 Hyundai Elantra · Power Train · filed with NHTSA Sep 11, 2026 · ODI 11763653
I found a lot of debris of metals contaminated in the gear reduction oil when I changed my gear reduction oil. I had a Vortex oil lug nut, which it sucks all of the metal debris in. I have pictures of that as a proof. I think this is a design flaw that Hyundai should recall, but they didn’t.
2022 Hyundai Kona · Power Train · filed with NHTSA Aug 21, 2025 · ODI 11682034
A complaint is one owner’s account, not a defect finding, and a bulletin is not a recall. Nothing here says this bulletin was issued because of these complaints, or that the repair it describes fixed them. Complaint files on this site begin in 2015.
More bulletins about the power train
Source: same model, same component group6 other manufacturer communications filed against these Hyundai models under the same component group (power train), newest first.
| Number | Kind | Dated | NHTSA’s summary |
|---|---|---|---|
| TDR | Service campaign | Jul 8, 2025 | Certain 2024MY Kona Electric (SX2 EV) and 2023-2024MY IONIQ 5 (NE EV) vehicles are equipped with a Motor and Reduction Gear System, also kno… |
| 24-AT-002H | Service bulletin | Apr 9, 2024 | This TSB provides a procedure to diagnose and replace, if necessary, an automatic transmission with Incorrect Ratio DTC… |
| 23-01-073H-1 | Service bulletin | Oct 17, 2023 | Certain 19-23MY Kona Electric (OS EV) vehicles may experience a condition of EV warning light ON with Diagnostic Trouble Code (DTC) P1AA6 to… |
| 23-01-073H | Service bulletin | Aug 29, 2023 | Certain 19-23MY Kona Electric (OS EV) vehicles may experience a condition of EV warning light ON with Diagnostic Trouble Code (DTC) P1AA6 to… |
| 23-AT-013H | Service bulletin | Aug 28, 2023 | This bulletin provides information related to a Transmission Control Unit (TCU) software update for certain vehicles equipped with an 8-spee… |
| 23-AT-010H | Service bulletin | Aug 23, 2023 | Certain vehicles equipped with the Intelligent Variable Transmission (IVT) may experience a check engine light or malfunction indicator ligh… |
Quote the number at the service desk. It is what the dealer’s system is keyed on.
Every manufacturer communication NHTSA holds for Hyundai, by the number printed on the letter.
Common questions
Source: NHTSA, 49 CFR 579.5Is Hyundai 26-AT-004H a recall?
No. A service bulletin is a manufacturer communication filed with NHTSA under 49 CFR 579.5; a safety recall carries an NHTSA campaign number (two digits, a letter, six digits) and a federal duty to repair for free. Check the vehicle’s recalls by VIN at nhtsa.gov/recalls, or on its page here.
Is the 26-AT-004H repair free?
Not automatically. A service bulletin describes how to diagnose or repair a condition; who pays depends on the warranty in force, any extension, and the dealer. Quoting the number can save a diagnosis either way. Every Hyundai warranty extension on file lists the ones Hyundai has filed.
Which vehicles does 26-AT-004H cover?
The manufacturer filed it against 9 model years: 2026 Hyundai Elantra, 2025 Hyundai Elantra, 2024 Hyundai Elantra, 2023 Hyundai Elantra, 2022 Hyundai Elantra, 2023 Hyundai Kona and more. Whether one particular vehicle is affected is a matter of its VIN and its build, not its model year alone.