2021-2022 Hyundai Elantra ICU Software Update for Warning Lights

Hyundai has identified a software issue affecting the Integrated Central Control Unit (ICU) in certain 2021-2022 Hyundai Elantra, Elantra (CN7a), and Elantra Hybrid (CN7 HEV) vehicles. This issue can lead to several noticeable problems for owners, impacting vehicle operation and safety.

This bulletin, identified as Service Campaign T8T, provides a software update to correct the ICU's programming. The Hyundai Elantra ICU update is crucial for resolving these conditions and ensuring proper vehicle function.

Important Warnings

Hyundai has issued a critical directive for 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 that if you own an affected vehicle, your dealer is obligated to perform this update. If you are purchasing a new or used 2021-2022 Elantra, ensure this update has been completed.

Symptoms

Owners of affected 2021-2022 Hyundai Elantra vehicles may experience one or more of the following symptoms:

• "multiple warning lights displayed on the instrument cluster"
• "reduction in power steering assist"
• "not able to shift out of Park"

These symptoms are often accompanied by specific Diagnostic Trouble Codes (DTCs) stored in the vehicle's computer system.

Fault Codes / DTCs

The following Diagnostic Trouble Codes (DTCs) may be set in conjunction with the symptoms described:

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 issue is diagnosed by checking the current software version (ROM ID) of the Integrated Central Control Unit (ICU) and comparing it to the updated versions provided by Hyundai. If the vehicle's ICU software is outdated, the update is required. The diagnostic process involves using the GDS-Mobile system to read the ROM ID.

ROM ID Information Table

Model	System	ICU P/N	Old ROM ID	New ROM ID
Elantra (CN7)	ICU	91950-AA010 ~ 91950-AA990, 91951-AA010 ~ 91951-AA590	1.02, 1.03, 1.04, 1.05	1.06
Elantra (CN7a)	ICU	91950-AB000 ~ 91950-AB060	4.02, 4.03	4.04
Elantra Hybrid (CN7 HEV)	ICU	91950-BY010 ~ 91950-BY240	3.03, 3.04, 3.05, 3.06	3.07

Repair Procedure Summary

The repair involves updating the ICU software using the GDS-Mobile diagnostic tool. The process can be performed in either Auto Mode or Manual Mode.

1. Preparation: Ensure the vehicle's battery is above 12 volts. If the vehicle has been in storage, run the engine to charge the battery. Turn off all lamps and accessories (heater, A/C, blower, radio, seat warmer, defroster) to prevent battery discharge during the update. The ignition switch must be in the ON position.

2. Connect GDS-Mobile: Connect the VCI-II to the vehicle's DLC connector and ensure the Tablet PC used for GDS-Mobile is sufficiently charged.

3. Software Update (Auto Mode): Select "ECU Upgrade" and then "Auto Mode" on the GDS-Mobile screen. Select "ICU" as the system to update. The system will perform an ID check and identify the correct update event, such as "851.CN7 ICU LOGIC IMPROVEMENT" for CN7 models. Confirm the battery voltage is sufficient (at least 12V). The update will proceed in two stages (1/2 and 2/2). Once complete, follow the on-screen instructions to turn the ignition off for 10 seconds and then back on.

4. Software Update (Manual Mode - if Auto Mode fails): If the Auto Mode update fails, turn the ignition key off for 10 seconds, then back on. Re-enter the ECU Upgrade menu and select "Manual Mode." Select ICU and the correct event. For manual mode, a password is required:

   Event #	Menu	Password
   #851 - CN7	CN7 ICU 91950/91951-AAXXX	5051
   #852 - CN7a	CN7a ICU 91950 - ABXXX	5060
   #864 - CN7 HEV	CN7 HEV ICU 91950-BY010~BY240	5019

   Proceed with the update as in Auto Mode.

5. Post-Update: After the update is complete, remove the power connector of the indoor fuse box and reconnect it after 5 seconds. Check for and clear any incidental Diagnostic Trouble Codes (DTCs) that may have been created during the upgrade. Start the engine to confirm proper vehicle operation. Refer to TSB 15-GI-001 for tablet-based Mobile GDS ECU update procedures.

Required Tools or Parts

To perform the Hyundai Elantra ICU update, technicians will utilize the GDS-Mobile diagnostic system, including the VCI-II interface and a Tablet PC. The causal part numbers associated with this service campaign are 91951-AA010 (CN7), 91950-BY110 (CN7 HEV), and 91950-AB060 (CN7a).

Owner Action

If your 2021-2022 Hyundai Elantra is exhibiting symptoms such as "multiple warning lights displayed on the instrument cluster," "reduction in power steering assist," or if you are "not able to shift out of Park," you should contact your authorized Hyundai dealer. This software update is performed under Service Campaign T8T and should be completed free of charge. The dealer will check your vehicle's current ICU software version and perform the necessary Hyundai Elantra ICU update.

NHTSA ID: 10222083