2021-2022 Hyundai Elantra DTC C1620 Front Radar Issue

Symptoms

Owners of certain 2021-2022 Hyundai Elantra (CN7/CN7A) vehicles may observe a warning light illuminated on the dashboard, accompanied by the diagnostic trouble code (DTC) C1620. This issue can also lead to the inoperability of critical Advanced Driver Assistance Systems (ADAS) such as Smart Cruise Control (SCC) and Forward Collision-Avoidance Assist (FCA). Other ADAS functions are typically not affected by this specific problem. If your Hyundai Elantra DTC C1620 appears, it indicates a problem with the front radar system.

Fault Codes / DTCs

The primary diagnostic trouble code associated with this issue is:

Diagnosis

The root cause of the DTC C1620 and the related system malfunctions is a distorted signal from the front radar reception antenna. This distortion is often due to internal contamination within the radar unit itself. The issue prevents the radar from accurately detecting objects and maintaining proper calibration.

Repair Procedure Summary

To resolve the Hyundai Elantra DTC C1620 and associated issues, the front radar unit must be replaced and properly calibrated. The repair procedure involves several key steps:

1. Front Radar Unit Replacement: The affected front radar unit (part A in the service manual diagrams) is removed and replaced with a new one. Technicians must follow the detailed instructions in the Shop Manual under the 'Advanced Driver Assistance System (ADAS) > Front Radar System > Front Radar Unit > Repair procedures' section.
2. System Configuration: After installation, variant coding is performed to ensure the new radar unit is correctly integrated with the vehicle's systems.
3. Alignment and Adjustment: The mounting angle of the new radar unit must be precisely aligned and adjusted. This critical step ensures accurate sensor readings for the ADAS functions.
4. Documentation: Technicians are required to take specific validation photos using the STUI system. This includes images of both the old and new front radar units, clearly showing the last 6 digits of the VIN and the repair date. A screenshot of the 'Alignment complete' screen from the diagnostic tablet must also be uploaded.
5. Post-Adjustment Driving: Once alignment is complete and the criteria for normal operation are met (vertical angle -2 to 0 degrees, horizontal angle -2 to +2 degrees), it is recommended to drive the vehicle for a minimum of 10 minutes at no less than 40 MPH to further improve radar precision.
6. Reassembly: All components are reassembled in the reverse order of removal.

Required Tools and Parts

To perform this repair, specific parts and special service tools (SSTs) are necessary:

• Front Radar Unit: Part Number 99110-AA000QQH (for Elantra CN7, CN7A). Note that due to a labeling error, the part label may not include 'QQH' at the end, but the box enclosing the part should state '99110-AA000QQH'.
• Reflector: Tool Number 09664-C1100
• Laser: Tool Number 09664-C1200
• Tripod: Tool Number 09664-C1300
• Reflector Adapter: Tool Number OK964-J5100

These essential tools were previously shipped to all Hyundai dealers. Additional units can be ordered directly from BOSCH by calling 1-866-539-4248.

Owner Action

If you experience a warning light with DTC C1620, or if your Smart Cruise Control (SCC) or Forward Collision-Avoidance Assist (FCA) systems are inoperative in your 2021-2022 Hyundai Elantra, you should contact your authorized Hyundai dealer. The repair involves replacing the front radar unit and performing a precise calibration. This service is typically covered under warranty as a campaign-type claim. If other components are found to be faulty during this repair, and they are still under warranty, a separate claim will be submitted. For parts out of warranty, a Prior Approval request for goodwill consideration may be submitted by the dealer.

NHTSA ID: 10252366