2022-2024 Audi Lane Change Assist C12BFF0 Fault TSB

Owners of 2022-2024 Audi vehicles, including the Audi e-tron, may experience an inoperative intersection/lane change assist system, accompanied by the diagnostic trouble code C12BFF0. This issue, often referred to as an Audi e-tron C12BFF0 fault, is detailed in Technical Service Bulletin (TSB) 2063336/3, issued on March 8, 2023. This bulletin supersedes TSB Group 96 number 21-74 dated November 24, 2021.

Symptoms

When the intersection or lane change assist system is inoperative, drivers may notice one of the following messages displayed in the instrument cluster:

• "Intersection assist: fault. Please contact workshop."
• "Side assist and exit warning system: fault. Please contact workshop."
• "Rear cross-traffic assist: fault. Please contact workshop."
• "Audi pre sense: fault. Please contact workshop."

Fault Codes / DTCs

Technicians investigating this issue will likely find the following Diagnostic Trouble Code (DTC) stored in one of the lane change assist control modules (J769/J770) or the radar sensor control module for object detection (J1088/J1089):

Code	Description
C12BFF0	Radar sensor automatic calibration not possible

Technical Background

The affected sensors continuously calibrate themselves in relation to the vehicle's surroundings while driving above a certain speed threshold. If the calculated dynamic angle offset exceeds +/-5° during this automatic calibration process, the DTC C12BFF0 is logged, and the corresponding warning messages appear in the instrument cluster. This indicates a problem with the sensor's ability to maintain proper calibration.

Possible Causes

Several factors can lead to the Audi e-tron C12BFF0 fault and inoperative assist systems:

• Sensors that are loose or not fully seated in their mounts.
• Incomplete calibration of sensors after a previous replacement.
• Obstructions like decals, stickers, or NFC tags in the sensor's field of view on the bumper cover (inside or outside).
• Excessive dirt accumulating in the sensor's field of view.
• Damage to the bumper cover in the sensor's field of view.
• Inadequate or non-conforming paintwork on the bumper cover, affecting the sensor's field of view.

Repair Procedure Summary

Before proceeding with sensor replacement, technicians should first check for and remedy any of the possible causes listed above. If the cause is not clearly identifiable and sensor calibration continues to fail, the following steps are recommended:

1. Remove the affected sensor from its mount, then reseat it properly. Afterward, perform the calibration procedure again.
2. If calibration still fails, swap the left and right sensors. Note that after swapping, a full replacement procedure must be performed using ODIS-S to ensure the correct data set is available for subsequent calibration. Once completed, perform calibration again.

Important Warnings

Audi advises that to calibrate the sensors, the dynamic calibration procedure should be used. It is important to note that replacing the corresponding radar sensor without clear findings will NOT resolve the issue if the underlying cause is not addressed.

Warranty Information

Warranty claims for this issue are covered for up to 48 months or 50,000 miles. For Certified Pre-Owned (CPO) vehicles, G10 verification is required. If the vehicle is outside of warranty, this Technical Service Bulletin serves as informational guidance only.

Labor operations are specified depending on the affected control module, with diagnostic time allocated for GFF (Guided Fault Finding) procedures. Road tests before and after the service procedure are also accounted for.