2022-2026 Audi e-tron GT DTC C1399F0 in ABS Module

Audi has issued Technical Service Bulletin (TSB) 43 24 99 2063679/5 to address instances where Diagnostic Trouble Code (DTC) C1399F0 may be stored in the Anti-lock Braking System (ABS) control module of 2022-2026 Audi e-tron GT, RS e-tron GT, and S e-tron GT vehicles. This bulletin clarifies that the presence of DTC C1399F0 is usually a normal operational condition related to the brake system's break-in process.

This TSB, identified as 43 24 99 2063679/5, supersedes a previous bulletin, Group 45 number 24-38, dated January 12, 2024. The latest revision, dated September 10, 2024, includes updated information regarding the technical background and warranty details.

Symptoms

Owners of affected Audi e-tron GT models may notice specific conditions that lead to the storage of DTC C1399F0. These include:

• Experiencing "Recuperation too low when braking on new vehicle."
• Observing this condition after brake discs and/or brake pads have been replaced.

Fault Codes / DTCs

Workshops investigating these symptoms may find the following diagnostic trouble code stored in the ABS control module, designated as -J104- (address word 0003):

Code	Description
C1399F0	Brake application mode active

Technical Background

Audi has implemented a brake application mode designed to properly break in new brake pads on the discs. This mode is activated on new vehicles or whenever brake discs and/or pads are replaced. Technicians can initiate this process using the ODIS diagnostic system via the function "003 Brake-In Service Brakes."

During this break-in period, the vehicle's energy recuperation function is temporarily deactivated, and braking is performed manually. The system logs DTC C1399F0 in the ABS control module (J104) to indicate that this special brake application mode is active. Importantly, this process is not actively displayed to the driver in the instrument cluster or the MMI system.

The brake application mode and the associated DTC C1399F0 will automatically deactivate once the required amount of braking energy has been applied, signaling that the break-in process is complete. The progress of this break-in can be monitored by technicians using the measured value "Progress of the break-in of service brakes" in the ABS control unit.

Important Warnings for Owners

Owners should be aware of specific details regarding this condition:

• "No measure is necessary" to address the DTC C1399F0 when it is related to the brake break-in mode, as it is a normal operational state.
• "This TSB is informational only and not applicable to any Audi Warranty." This means that any diagnosis or repair related to this specific condition, if not covered by other warranty terms, would not be covered under this bulletin.

What This Means for Your Audi e-tron GT

If you own a 2022-2026 Audi e-tron GT, RS e-tron GT, or S e-tron GT and experience the symptoms described or have DTC C1399F0 identified, it is likely part of the normal brake system break-in process. The Audi e-tron GT C1399F0 code is generally self-resolving as you drive and use the brakes normally. There is typically no need for concern or immediate service action for the Audi e-tron GT C1399F0 code itself.

NHTSA ID

11009345