2025-2026 Hyundai Tucson DCU Software Update

Hyundai has released Technical Service Bulletin (TSB) 25-01-061H-1, also known as Service Campaign TDFC, to address a software issue affecting the Data Communication Unit (DCU) in certain 2025-2026 Hyundai Tucson (NX4A) vehicles. This bulletin supersedes previous TSB 25-01-061H and provides updated information for VCI 2 connection and IP settings on pages 4-5.

Important Warnings for Owners and Technicians

This service campaign is critical and dealers must perform the update on all affected vehicles prior to customer retail delivery. It also applies whenever an affected vehicle is in the shop for any maintenance or repair. Dealers can identify open campaigns by accessing the “Vehicle Information” screen via WebDCS.

For technicians performing the update, several precautions are necessary:

• You must initially perform the GDS ECU update in Auto Mode. If the ECU update starts but then fails in Auto Mode, you should perform it in Manual Mode to recover.
• Ensure the vehicle's battery charge is above 11.0 Volts and the tablet's battery charge is above 30% before performing the software update to prevent failure.
• Turn OFF all lamps (do NOT leave the headlamp switch in auto mode) and all accessories.
• Do NOT disconnect any cables connected to the vehicle or scan tool during the update.
• Do NOT start the engine during the update.
• Do NOT turn OFF the ignition switch during the update.
• If using VCI 2, wait for the Wi-Fi Direct timer to complete to establish the connection. Do NOT select Bluetooth Only.
• If the update fails, remove the power connector from the in-cabin fuse box for at least 5 seconds, or disconnect the negative (-) 12V battery terminal for at least 5 seconds. Then reassemble and retry the update.
• The VIN/Date/Time/Mileage photo imprint is NOT required for GDS screenshots.

Symptoms of the DCU Software Error

Owners of affected 2025-2026 Hyundai Tucson (NX4A) vehicles may experience a Hyundai Tucson DCU software error where the Data Communication Unit (DCU) module may shut down telematics services after one year of operation. This is due to an internal timer initialization logic not being properly implemented within the DCU software.

Diagnosis and Trigger Conditions

The root cause of the telematics shutdown is an internal timer initialization logic that is not correctly implemented within the DCU software. This condition affects certain Tucson (NX4A) models, specifically those with the ECU Part Number 96510-N9140. The GDS information describes this as