2021 Hyundai Elantra Engine Stall TSB

Why This Matters

Hyundai has identified a potential issue in certain 2021 Elantra vehicles that could lead to an engine stall. While the engine can be immediately restarted, an unexpected stall, particularly after the Forward Collision Avoidance (FCA) system activates, can be a safety concern. This Technical Service Bulletin (TSB) outlines a software update designed to prevent this specific condition, ensuring consistent vehicle operation and driver confidence.

Symptoms

Owners of affected 2021 Hyundai Elantra vehicles may experience an engine stall condition. This stall is specifically noted to occur immediately after the Forward Collision Avoidance (FCA) system activates. The good news is that if a low-speed stall does occur, the engine can be restarted right away.

Diagnosis / Trigger Conditions

The engine stall condition is linked to the Forward Collision Avoidance (FCA) system activation. It typically manifests under specific operating conditions, including low engine RPM and low vehicle speeds. The issue stems from the Intelligent Variable Transmission (IVT) damper clutch logic, which requires an update to prevent the Hyundai Elantra engine stall.

Important Warnings and Dealer Directives

Hyundai has issued several critical directives regarding this service campaign:

• Mandatory Dealer Action: Dealers are required to perform this service campaign on all affected vehicles before customer retail delivery. It must also be completed whenever an affected vehicle is brought in for any maintenance or repair.
• STUI Picture Requirement: This TSB mandates a STUI (Service Time Used Information) picture for warranty claims. The picture must clearly show the VIN and the date of the repair. Specifically, the last 6 digits of the VIN and the repair date must be visible on a piece of paper placed next to the campaign sticker. Claims submitted without a proper STUI picture that fails to capture the VIN, repair date, or sticker are subject to debit. Illegible, incomplete, missing, or incorrect pictures will also result in debit.
• GDS-M Battery Voltage Warning: During the software update, if the vehicle battery voltage drops below 12 volts, the GDS-M system will display a "Warning! lower Battery Voltage. BATTERY VOLTAGE: 11.7" message (example value). To proceed, either connect a fully charged battery jump pack or GR8 charger using "Power Supply Mode," or exit the update, start the engine, and idle with headlights on for 20 minutes to charge the battery before resuming the update. Failure to follow these steps can cause the vehicle battery to die during the update, rendering the vehicle inoperable.
• Pre-Update Checks: Before starting the update, technicians must verify the vehicle battery has a reasonable charge, turn off all lamps and accessories (do not leave the headlamp switch in auto mode), ensure the ignition switch is in the ON position, and avoid disconnecting any cables or starting the engine during the update.

Warranty Information

This service campaign, identified as SERVICE CAMPAIGN 967, is covered under warranty. The operation codes and times are as follows:

• Elantra (CN7): Operation Code 10D035R3, Operation: TCU Upgrade & Sticker Install, 0.4 M/H (Man-Hours), Causal Part: 39171-2JCB5, Causal Code: T72, Nature Code: ZZ3.
• Elantra (CN7a): Operation Code 10D035R4, Operation: TCU Upgrade & Sticker Install, 0.4 M/H, Causal Part: 39171-2JBD5, Causal Code: T72, Nature Code: ZZ3.

Claims should be submitted via the Campaign Claim Entry Screen. If a separate part requires replacement and is under warranty, a separate warranty claim should be filed. For out-of-warranty parts, a Prior Approval Request for goodwill consideration is required.

Repair Procedure Summary

The repair involves updating the Transmission Control Unit (TCU) software using the GDS-M system. The procedure can be performed automatically or manually:

Automatic Update Procedure:

1. Perform the GDS-M software update as per TSB 15-GI-001.
2. Reset the TCU adaptive learning values.
3. Start the engine to confirm proper vehicle operation.

Manual Update Procedure (if automatic update fails): If the automatic update is unsuccessful, turn the ignition off for approximately 10 seconds, then turn it back on and reset the control unit.

1. From the GDS-M home screen, select "ECU Upgrade."
2. On the ECU Upgrade screen, select "Manual Mode," then choose "Update Event 677." The event description is "677.CN7/CN7a-TCU LOGIC IMPROVEMENT FOR IVT OPERATION."
3. When prompted for a password, enter "3917" and select "Upgrade."
4. Allow the update to complete.
5. After the update, turn the ignition off for 10 seconds, then back on. Check for any Diagnostic Trouble Codes (DTCs) that may have been created during the update and clear them.
6. Reset the TCU adaptive learning values.
7. Start the engine to confirm proper operation. The service procedure is then complete.

Required Parts and Documentation

To complete this service campaign, the following items are required:

• Campaign Sticker: Part Number 00305-SC967 (Quantity: 1). This sticker must be filled out and applied under the hood below the Emission Label. The mounting surface should be cleaned for proper adhesion.
• Vehicle Emission Recall - Proof of Correction Card: Part Number NP050-09006 (Quantity: 1). This card is specifically for vehicles registered in certain states.

The new ROM ID for the updated TCU software is CCN0N20NS5 for both Elantra (CN7) and Elantra (CN7a) models.

Proof of Correction Card for Specific States

For vehicles registered in California, Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington, a "Vehicle Emission Recall - Proof of Correction Card" (NP050-09006) must be completed. This card serves as evidence of voluntary service campaign completion and may be required for vehicle registration renewal. The card must be filled out neatly by the Dealership's Service Manager using a permanent ink pen, with information copied directly from the vehicle, not the repair order. The completed card should be given to the vehicle owner.

NHTSA ID: 10235306