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Service bulletin 26-AT-001H 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 id11029937
Published by NHTSA2026-03-11
Manufacturer's number26-AT-001H TSB
Manufacturer's date2026-03-03
NHTSA componentPOWER TRAIN

NHTSA's summary

Some Santa Cruz (NXT), Santa Fe (TMA, MX5A), and Sonata (DN8A) models may require replacement of the 8-speed wet dual clutch transmission (8WDCT) when the vehicle sets one of the high pressure electric oil pump (HP EOP) DTCs listed below. This bulletin provides instructions to replace the 8WDCT.

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 SANTA CRUZ2022, 2023, 2024, 2025
HYUNDAI SANTA FE2021, 2022, 2023, 2024, 2025
HYUNDAI SONATA2021, 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
20244042024-07-11. Powertrain
24V5290002024-07-11. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE
20225682022-10-06. Powertrain
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
26-AT-005H TSB2026-06-16. Service 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. Some 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.
26-01-028H2026-03-30. Warranty extension. Certain Santa Cruz (NXT) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may set one of the high pressure electric oil pump (HP EOP) DTCs listed below. This bulletin provides the service procedure to update the Transmission Control Unit (TCU) with improved logic to address these DTCs and enhance operation of the 8DCT.
26-AT-002H2026-02-24. Service bulletin. Some Santa Fe (TMA) and Tucson (NX4A) vehicles equipped with a 2.5L GDI engine and 8 speed automatic transmission may have DTC U028700 (Lost Communication With Trans Fluid Pump Module) set by the transmission Electric Oil Pump (EOP). This DTC can cause the Idle Stop & Go (ISG) system to become inoperative. Follow the procedure in this bulletin to replace the Electric Oil Pump on affected vehicles.
25-01-072H DCS2025-10-14. Service campaign. Hyundai Motor America is currently investigating an ongoing concern with software GDS event #1306 for certain Hyundai Santa Fe (MX5A) vehicles. The software update is not appearing for some impacted vehicles. In the interim, Technical Service Bulletin (TSB) 25-01-072H will be removed from Hyundai Tech Info. We will provide an update once the issue is resolved and the suspension is lifted. If dealer has already performed the update successfully on an impacted vehicle prior to the suspension, the corresponding campaign claim can be submitted.
25-01-071H/072H DCS2025-10-14. Service campaign. Certain Santa Fe (MX5A) and Santa Cruz (NXT) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may set one of the high pressure electric oil pump (HP EOP) DTCs listed below. Technical Service Bulletins (TSB) 25-01-071H (for Santa Fe vehicles) and 25-01-072H (for Santa Cruz vehicles) provide the service procedure to update the Transmission Control Unit (TCU) with improved logic to address these DTCs and enhance operation of the 8DCT.
25-01-072H TSB2025-10-13. Service campaign. Certain Santa Fe (MX5A) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may set one of the high pressure electric oil pump (HP EOP) DTCs listed below. This bulletin provides the service procedure to update the Transmission Control Unit (TCU) with improved logic to address the DTCs above and enhance operation of the 8DCT.
25-01-071H TSB2025-10-13. Service campaign. Certain Santa Cruz (NXT) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may set one of the high pressure electric oil pump (HP EOP) DTCs listed below. This bulletin provides the service procedure to update the Transmission Control Unit (TCU) with improved logic to address these DTCs and enhance operation of the 8DCT.
25-AT-001H TSB2025-06-03. Service bulletin. Certain Santa Fe (TMA) and Sonata (DN8/DN8A) vehicles equipped with 8-speed dual clutch transmissions (8DCT) may exhibit one of the DTCs listed below, related to the high pressure electric oil pump (HP EOP). Follow the procedures in this TSB to update the Transmission Control Unit (TCU) to the latest sensorless logic on affected vehicles, and then perform air bleeding and transmission learning.
24-AT-001H-12024-12-21. Service bulletin. This bulletin provides the procedure for updating the automatic transmission TCU (Transmission Control Unit) software to improve shift quality, judder and hesitation when accelerating.
24-AT-002H2024-04-16. Service bulletin. This TSB provides a procedure to diagnose and replace, if necessary, an automatic transmission with Incorrect Ratio DTC (transmission clutch slip in gear above limit) listed on Page 2.