2021 Hyundai Elantra ECM Update for Stalling and Blower Faults

What's the Issue?

Owners of certain 2021 Hyundai Elantra vehicles equipped with the 2.0L engine may experience issues related to the Engine Control Module (ECM) software. The primary concern is incorrect learning of fuel adaptive values, particularly when the engine is started in ambient temperatures of 14°F (-10°C) or colder. This can lead to the engine stalling when the vehicle comes to a stop or idles.

Additionally, the ECM software update addresses revised blower motor control duty cycle logic. This update is crucial for improving engine performance at idle and ensuring proper function of the blower motor.

Fault Codes / DTCs

This Hyundai Elantra ECM update specifically targets conditions that may trigger the following Diagnostic Trouble Codes (DTCs):

• P016C: Closed Loop Air/Fuel Ratio Control at Limit-System Too Lean. This code is associated with the incorrect fuel adaptation learning that can cause engine stalling.
• P1CD0: Air Blower Motor Inverter Performance. This code relates to the blower motor control logic.

Diagnosis and Trigger Conditions

The engine stalling issue, often accompanied by DTC P016C, is primarily triggered when the 2021 Hyundai Elantra's engine is started in cold ambient temperatures, specifically 14°F (-10°C) or colder. If incorrect fuel adaptive values are learned under these conditions, the engine's performance at idle or when coming to a stop can be negatively affected.

Repair Procedure Summary

The repair involves an ECM software update performed by a Hyundai dealership. Technicians will use the GDS Mobile system to update the ECM. The process generally follows these steps:

1. Perform the GDS Mobile software update as outlined in TSB 15-GI-001.
2. After the successful completion of the ECM software update, technicians will check for any remaining Diagnostic Trouble Codes (DTCs) across all vehicle menus and erase them.
3. Finally, normal vehicle operation will be confirmed.

It is critical that the GDS-M ECM Update is initially performed in Auto Mode. If the update fails to start or complete in Auto Mode, technicians are instructed to perform the update in Manual Mode to recover.

Important Notifications for Owners

Hyundai has issued this as a Service Campaign (T6R), meaning it's an important update. Dealers are required to perform this Service Campaign on all affected vehicles prior to customer retail delivery. It must also be performed whenever an affected vehicle is in the shop for any maintenance or repair.

Owners should be aware of a potential GDS-M Vehicle Battery Low Voltage Warning during the update process. If the vehicle battery voltage drops below 12 volts, the GDS-M system will display a warning: "Warning! lower Battery Voltage. BATTERY VOLTAGE: 11.7". If this occurs, the technician must either connect a fully charged battery jump pack or GR8 charger in “Power Supply Mode” to continue the update, or exit the update, run the engine with headlights on for 20 minutes to charge the battery, and then restart the update.

Required Tools or Parts

The primary requirement for this service campaign is the GDS Mobile software update system. The ECM upgrade itself is a software flash. The warranty information lists causal part numbers for the ECM upgrade as 39171-2JCB0 for Elantra (CN7) and 39171-2JBB5 for Elantra (CN7A).

Owner Action

If you own a 2021 Hyundai Elantra, especially one equipped with the 2.0L engine, and have experienced engine stalling in cold weather or noticed issues that might relate to the blower motor, you should contact your authorized Hyundai dealer. This is a service campaign, so the ECM software update will be performed free of charge. Your dealer can check your vehicle's eligibility using Hyundai Motor America's "Warranty Vehicle Information (VIS)" screen.

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Source: NHTSA ID: 10196551