2021 Hyundai Elantra Window Lockbox Battery Drain TSB

Hyundai has issued Technical Service Bulletin (TSB) 21-GI-005H to inform owners and dealerships about a potential Hyundai Elantra battery drain issue. This bulletin specifically addresses problems that can arise from using window-mounted lockboxes on 2021 Hyundai Elantra (CN7/CN7A) vehicles, particularly those without proper RFID shielding.

Symptoms

Owners of a 2021 Hyundai Elantra using certain window-mounted lockboxes may experience several issues. The primary symptom is a rapid battery drain, affecting both the vehicle's main battery and the key fob battery. This can lead to difficulty starting the car or needing frequent battery replacements for the key fob.

Beyond electrical problems, prolonged use of these lockboxes can also cause physical damage. The window run seal may become damaged, which could result in air leaks and noticeable wind noise while driving.

Diagnosis / Trigger Conditions

The root cause of the Hyundai Elantra battery drain is the continuous radio frequency (RF) transmission from the key fob. When a window-mounted lockbox without RFID shielding is placed on the rear window, the key fob inside remains within range of the vehicle's receiver. This constant proximity causes the key fob to continuously transmit an RF signal, which in turn keeps various vehicle systems active, leading to excessive power consumption.

This condition is particularly relevant for dealer stock vehicles where lockboxes are often used for key storage. The issue arises because the lockbox fails to block the RF signal, allowing the key fob to communicate with the vehicle constantly.

Important Warnings

Hyundai has issued several critical warnings regarding the use of window-mounted lockboxes:

• "When the lockbox is mounted to the rear window, the key fob will continuously transmit a RF signal because it is still within the range of the receiver. This may drain the vehicle battery and the key fob battery."
• "Prolonged use of window mounted lockboxes may cause damage to the window run seal, leading to air leak and wind noise."
• "It is not recommended to use window mounted lockboxes for more than 24 hours to prevent permanent seal damage."
• "Battery drain or window seal damage caused by lockboxes may void the factory warranty."
• "Damage or wind noise related repairs resulting from the use of a lockbox are not covered under warranty. Parts may be called back for inspection by the Warranty Technical Center and the claim will be subject to charge back."

These warnings highlight the potential for significant issues, including the risk of voiding your vehicle's factory warranty for related repairs.

Recommended Preventative Measures

To prevent the Hyundai Elantra battery drain and other related issues, Hyundai recommends using window-mounted lockboxes that are equipped with RFID shielding. This shielding is designed to block the RF signal from the key fob, preventing it from continuously transmitting to the vehicle's receiver. By doing so, the vehicle's electrical systems can properly power down, conserving battery life.

Additionally, it is advised to limit the duration for which window-mounted lockboxes are attached to the vehicle. Specifically, avoid using them for more than 24 hours at a time to prevent permanent damage to the window run seal.

Owner Action

If you own a 2021 Hyundai Elantra and use a window-mounted lockbox, it is crucial to ensure it has RFID shielding. If your current lockbox does not have this feature, consider replacing it with one that does. Be aware of the potential for battery drain and physical damage to your vehicle's window seals. Any repairs for issues directly caused by these lockboxes may not be covered under your factory warranty.

Consult your Hyundai dealer if you have concerns about battery drain or window seal integrity, especially if you have been using a non-RFID shielded lockbox.

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Source: NHTSA ID: 10196583