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Service campaign TDQ/TDQA WebDCS

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 campaign
NHTSA id11023041
Published by NHTSA2025-09-09
Manufacturer's numberTDQ/TDQA WebDCS
Manufacturer's date2025-09-04
Campaign id or software versionTDQ/TDQA
NHTSA componentELECTRICAL SYSTEM

NHTSA's summary

Hyundai Motor America is currently investigating an ongoing auto mode update concern with software GDS event #1243. Some vehicles are not being able to complete the update after multiple attempts. Technicians may experience consistent cluster speedometer software upgrade failures when attempting to update to the latest version. A revised version of the software is currently in development to address the update failures and recover any failed modules. We will provide an update once the issue is resolved and the suspension is lifted.

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

Vehicles listed
HYUNDAI SONATA2024, 2025
HYUNDAI SONATA HYBRID2024, 2025 (the catalog's model; the bulletin names a series or trim of it)

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
LA29-LA30 DCS2026-07-21. Warranty extension. Certain 2024-2026MY Sonata (DN8) and 2024-2026MY Sonata Hybrid (DN8 HEV) vehicles may exhibit intermittent battery discharge condition due to the air conditioning controller not fully powering down after the vehicle is turned off and parked. Technical Service Bulletins (TSB) 26-01-051H & 26-01-052H provide the procedure to update the ATCU (Air Temperature Control Unit) software; the revised logic improves controller shutdown to prevent battery drain and corrects a condition where the HVAC control display may appear blank when climate remote start is activated via Bluelink. Over-the-Air (OTA): This update can also be conducted via OTA. Customers can complete on their own if they have an active subscription to Hyundai Bluelink. A visit to the dealership is not required. Deployment of the OTA to Bluelink customers is planned to start the week of 07/13/26.
26-01-052H TSB2026-07-21. Warranty extension. Certain Sonata Hybrid (DN8 HEV) vehicles may exhibit intermittent battery discharge conditions due to the air conditioning controller not fully powering down after the vehicle is turned off and parked. This bulletin provides the procedure to update the Air Temperature Control Unit (ATCU) software; the revised logic improves controller shutdown to prevent battery drain and corrects a condition where the HVAC control display may appear blank when climate remote start is activated via Bluelink.
7/13/2026 TSB2026-07-21. Warranty extension. Certain Sonata (DN8) vehicles may exhibit intermittent battery discharge condition due to the air conditioning controller not fully powering down after the vehicle is turned off and parked. This bulletin provides the procedure to update the ATCU (Air Temperature Control Unit) software; the revised logic improves controller shutdown to prevent battery drain and corrects a condition where the HVAC control display may appear blank when climate remote start is activated via Bluelink.
26-GI-002H TSB2026-06-06. Service bulletin. This bulletin provides information related to the navigation and head unit software changes introduced in the 2026 1st Navigation Map and Software Update. The changes may vary depending on vehicle type, model, and navigation system. Refer to the 2026 1st Navigation Map and Software Update Key Improvements and Additional Improvements tables in this TSB for a list of specific changes. The software can be downloaded via Navigation Updater (NAU) and updated by USB.
26-01-035H TSB2026-04-15. Service campaign. Some vehicles may exhibit a loss of connectivity or interruptions in the middle of using Bluelink functions. This may be due to an occasional disconnection on Verizon’s communication network. Follow the procedures in this bulletin to verify Bluelink Data Communication Unit (DCU) network connection and if needed, reset the DCU in Dealer Mode to resolve the connection.
26-EM-009H TSB2026-03-30. Service bulletin. Some Sonata (DN8) and Tucson (NX4/NX4A/NX4M) vehicles equipped with the 2.5L Theta III GDI engine may display a warning lamp and store Diagnostic Trouble Code (DTC) P2B59F0, which relates to the Integrated Thermal Management Module (ITM) circuit due to a logic error. This bulletin provides instructions to update the Engine Control Module (ECM) logic to correct this condition.
TEB/TEBA DCS2025-12-16. Service campaign. Hyundai Motor America is currently investigating an ongoing issue with software GDS event #1302. The matter is being investigated. We will provide an update once the issue is resolved and the suspension is lifted.
25-01-075H/076H DCS2025-10-29. Service campaign. Certain Sonata (DN8) and Sonata Hybrid (DN8 HEV) vehicles may experience battery drain due to the air conditioning controller not shutting down completely while the vehicle is parked and turned off. TSBs 25-01-075H (for Sonata vehicles) & 25-01-076H (Sonata Hybrid vehicles) provides instructions to perform a software update for the ATCU (Air Temperature Control Unit).
25-01-076H TSB2025-10-29. Service campaign. Certain Sonata Hybrid (DN8 HEV) vehicles may experience battery drain due to the air conditioning controller not shutting down completely while the vehicle is parked and turned off. This bulletin provides instructions to perform a software update for the ATCU (Air Temperature Control Unit).
25-01-075H TSB2025-10-28. Service campaign. Certain Sonata (DN8) vehicles may experience battery drain due to the air conditioning controller not shutting down completely while the vehicle is parked and turned off. This bulletin provides instructions to perform a software update for the ATCU (Air Temperature Control Unit).