2021-2022 Hyundai Elantra ICU Software Update TSB

Important Warnings

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 means the update should be applied to new vehicles before sale and to any affected vehicle brought in for service.
• Dealers should "Access the 'Vehicle Information' screen (VIS) via WEBDCS to identify open campaigns."
• During the ECU upgrade process, technicians are warned: "DO NOT start the engine and DO NOT turn the ignition key to the OFF position during the ECU upgrade."
• It is crucial "Do NOT disconnect the communication with vehicle during upgrading the ECU!!"
• Technicians must "Do not disconnect any cables connected to the vehicle or scan tool during upgrade."
• Also, "Do not start the engine during upgrade" and "Do not turn off the ignition switch during upgrade."
• Finally, "Do not touch the systems buttons (like ‘BACK', ‘HOME', 'etc.') while performing upgrade."
• If the battery voltage is below 12 volts, a warning "Warning! lower Battery Voltage. BATTERY VOLTAGE: 11.5" may appear, and the engine must be run to ensure adequate charge before proceeding.

Symptoms

Owners of certain 2021-2022 Hyundai Elantra (CN7, CN7a) and Elantra Hybrid (CN7 HEV) vehicles may experience a combination of the following issues:

• Multiple warning lights displayed on the instrument cluster.
• Reduction in power steering assist.
• Inability to shift the vehicle out of Park.

These symptoms are often accompanied by specific Diagnostic Trouble Codes (DTCs) stored in the vehicle's computer system. This Hyundai Elantra ICU software update aims to correct these underlying issues.

Fault Codes / DTCs

The following Diagnostic Trouble Codes (DTCs) may be set in affected vehicles:

Code	Description	Module
C181287	CAN Time-out Gateway	ICU
C181208	CAN Time-out Gateway	ICU
C180581	LKAS CAN Signal Error	ICU
C181887	CAN Time-out BCA	ICU
B109052	TCU Missing Error	ICU

Diagnosis / Trigger Conditions

The issues described, including the various warning lights and functional limitations, are triggered by internal software logic within the Integrated Central Control Unit (ICU). The presence of the listed DTCs confirms the need for the Hyundai Elantra ICU software update. This condition affects certain vehicles produced within specific date ranges:

• 2021MY Elantra (CN7) vehicles produced from September 12, 2020 – June 1, 2021.
• 2021-2022MY Elantra (CN7a) vehicles produced from September 25, 2020 – September 27, 2021.
• 2021-2022MY Elantra Hybrid (CN7 HEV) vehicles produced from December 15, 2020 – August 11, 2021.

Repair Procedure Summary

The repair involves updating the software of the Integrated Central Control Unit (ICU) using the GDS-Mobile diagnostic system. This procedure is identified as Service Campaign T8T.

1. Initial Check: Technicians must first check the vehicle's current ICU ROM ID and compare it to the ROM ID Information Table provided in the bulletin to confirm if an update is required. The battery voltage must be above 12 volts; if not, the engine should be run to charge it.
2. Connect Diagnostic Tool: The VCI-II (Vehicle Communication Interface) is connected to the vehicle's DLC connector. The GDS-Mobile tablet PC, which must be sufficiently charged, is used for the update.
3. Software Update (Auto Mode): The update is typically performed in "Auto Mode" via the GDS-Mobile system. The technician selects "ECU Upgrade" and then "ICU" as the system to update.
4. Confirm Event: The correct software update event (e.g., "851.CN7 ICU LOGIC IMPROVEMENT" for CN7 models) is selected based on the vehicle's model.
5. Monitor Progress: The upgrade process occurs in two stages (1/2 and 2/2), with progress displayed on a bar graph. Technicians must ensure stable communication and avoid interrupting the process.
6. Post-Update Steps: Once the upgrade reaches 100%, the ignition is cycled off for 10 seconds and then back on. After the update is complete, the power connector of the indoor fuse box is removed and reconnected after 5 seconds.
7. Final Verification: Any incidental DTCs generated during the update are cleared, and the engine is started to confirm proper vehicle operation.

Required Tools or Parts

The following tools and information are necessary for performing this service campaign:

• GDS-Mobile: Global Diagnostic System-Mobile tablet PC.
• VCI-II: Vehicle Communication Interface.
• TSB 15-GI-001: For detailed tablet-based Mobile GDS ECU update procedures.
• Causal Part Numbers (for warranty claims):
  • 91951-AA010 (for Elantra CN7)
  • 91950-BY110 (for Elantra Hybrid CN7 HEV)
  • 91950-AB060 (for Elantra CN7a)

Owner Action

If you own a 2021-2022 Hyundai Elantra (CN7, CN7a) or Elantra Hybrid (CN7 HEV) and are experiencing multiple warning lights, reduced power steering assist, or difficulty shifting from Park, it is recommended to contact your authorized Hyundai dealership. This Hyundai Elantra ICU software update is a service campaign (T8T) and should be performed by the dealer. The bulletin indicates that dealers must perform this update on affected vehicles prior to retail delivery or whenever the vehicle is in the shop for maintenance or repair. The repair time is estimated at 0.3 hours.

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NHTSA ID: 10225460