2025 Hyundai Tucson Battery Discharge TSB 25-01-021H

Certain 2025 Hyundai Tucson (NX4) vehicles may encounter an issue where the vehicle's battery discharges prematurely. This problem stems from a logic error within the Central Communication Unit (CCU), which manages various communication functions in the vehicle.

Hyundai has released Technical Service Bulletin 25-01-021H, titled "CENTRAL COMMUNICATION UNIT (CCU) MULTIPLE SUBSYSTEM SOFTWARE UPDATE (SERVICE CAMPAIGN TCT)", to address this concern. The bulletin provides detailed instructions for technicians to update the software for both the MCU (Microcontroller Unit) and AP (Application Processor) subsystems related to the CCU, aiming to improve its overall logic and prevent the battery discharge.

Symptoms

Owners of affected 2025 Hyundai Tucson vehicles may notice that their vehicle's battery drains unexpectedly, even when the vehicle is not in use. This can lead to difficulties starting the vehicle or other electrical system malfunctions.

Fault Codes / Event Numbers

While no traditional DTC (Diagnostic Trouble Code) is explicitly mentioned, the software update addresses specific internal system events related to the CCU's logic improvement:

• Event Number 1190: NX4 PE (HEV) CCU PNC LOGIC IMPROVEMENT (AP)
• Event Number 1191: NX4 PE (HEV) CCU PNC LOGIC IMPROVEMENT (MCU)

Both of these update events, 1190 and 1191, must be successfully performed to resolve the underlying logic error causing the 2025 Hyundai Tucson battery discharge.

Diagnosis / Trigger Conditions

The battery discharge is triggered by an internal logic error within the Central Communication Unit (CCU). This issue can be identified by dealers using the WebDCS system to check for open campaigns related to the vehicle. The software update is designed to correct this internal logic, thereby preventing the battery from discharging.

Important Warnings for Owners and Technicians

Hyundai has issued several critical advisories regarding this service campaign:

• Dealers must perform this service campaign on all affected vehicles prior to customer retail delivery and whenever an affected vehicle is in the shop for any maintenance or repair.
• This software update is subject to an OTA (Over-the-Air) option and may be completed by customers with active Bluelink subscriptions.
• Both update events (1190 and 1191) must be performed to qualify for claim submission and prevent claim rejection.
• For the update procedure, the vehicle's battery charge must be above 11.0 Volts, and the diagnostic tablet's battery charge must be above 30% to avoid update failure.
• Technicians are instructed to do NOT leave the headlamp switch in auto mode and turn off all accessories during the update.
• 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 the ECU update fails, the power connector or battery (-) connector from the indoor fuse box should be removed for at least 5 seconds and reassembled before retrying the update.

Repair Procedure Summary

The repair involves updating the software of the Central Communication Unit (CCU) using specialized diagnostic tools. The process for addressing the 2025 Hyundai Tucson battery discharge includes:

1. Preparation: Ensure the vehicle's battery is adequately charged (above 11.0 Volts) and the diagnostic tablet is sufficiently charged (above 30%). All lamps and accessories must be turned off.
2. Tool Connection: Connect the diagnostic equipment, such as the VCI 3 or VCI 2 with an Ethernet Communication Interface (ECI) Kit, to the vehicle's OBD connector.
3. First ECU Update (AP): Perform the first of two required ECU updates in Auto Mode for the Application Processor (AP) subsystem (Event 1190). Technicians must use the ID Check function to verify the ROM ID before proceeding.
4. Post-Update Reset: After the AP update reaches 100% completion, cycle the ignition OFF for at least 10-30 seconds to reset the control unit.
5. OTA Initialization: Allow the Over-the-Air (OTA) initialization to perform automatically. If it fails, it must be performed manually through the S/W Management menu.
6. Fault Code Erase: Perform an All Systems Fault Code search and erase any DTC history that may have occurred incidentally due to the ECU update.
7. Power Cycle: Disconnect the power connector in the indoor fuse box for at least 5 seconds, then reconnect.
8. Second ECU Update (MCU): Perform the second required ECU update in Auto Mode for the Microcontroller Unit (MCU) subsystem (Event 1191). Again, verify the ROM ID using the ID Check function.
9. Final Steps: Start the engine to confirm proper operation of the vehicle. If any update fails in Auto Mode, a manual update can be attempted using specific passwords for each event.

Required Tools or Parts

Technicians will need specific tools to perform this software update:

• VCI 3 (Tool Number GOVHNNN06): Includes a 19-pin cable (P/N G1XDDCA020).
• VCI 2 (Tool Number G1XDDMN001): Requires the Ethernet Communication Interface (ECI) Kit (Tool Number G0XDDMN052) for software updates.

Software Versions

The software update targets the following ROM IDs for the Central Communication Unit (CCU), ECU Part Number 91920-N9000:

System	Software	Old Version	New Version
CCU	AP	1.32.39	1.32.51
CCU	MCU	1.32.19	1.32.21

Warranty Information

This service campaign, identified by Campaign Number 25-01-021H (Service Campaign TCT), has the following warranty details:

• Operation Code: 50D004R0
• Operation: CCU Update
• Operation Time: 0.4 M/H
• Causal Part: 91920-N9000
• Nature Code: W11
• Cause Code: ZZ3

Claims must be submitted as