2022-2023 Audi e-tron GT C1399F0 ABS Module DTC

Symptoms of Audi e-tron GT C1399F0

Owners of 2022-2023 Audi e-tron GT and RS e-tron GT models may experience specific symptoms related to this issue. The primary concern is a noticeable reduction in recuperation when braking, particularly if the vehicle is new or has recently had its brake discs and/or pads replaced. This condition indicates that the vehicle's regenerative braking system is not functioning at its full capacity.

Fault Codes / DTCs

The presence of the Audi e-tron GT C1399F0 fault code is a key indicator of this issue. This Diagnostic Trouble Code (DTC) is stored in the ABS control module, specifically the J104 unit (address word 0003).

Code	Description	Module
C1399F0	Brake application mode active	J104

Diagnosis and Trigger Conditions

The Audi e-tron GT C1399F0 code is typically triggered under specific circumstances related to the vehicle's brake system. Audi has implemented a "brake application mode" designed to properly break in new brake pads on the discs. During this break-in process, the vehicle's recuperation function is temporarily deactivated, and braking is performed manually. The DTC C1399F0 is logged in the ABS control module during this period.

It's important to note that this brake-in process, and the associated DTC, are not actively displayed to the driver in the instrument cluster or the MMI system. The system automatically deactivates this mode and clears the DTC once the necessary amount of energy has been dissipated, indicating the break-in process is complete. Therefore, if the DTC persists or low recuperation continues after sufficient driving, a service procedure is required.

Repair Procedure Summary

To address the Audi e-tron GT C1399F0 and restore normal recuperation, Audi Technical Service Bulletin 2063679/3 outlines a straightforward diagnostic and repair process for technicians. If the brake discs and/or pads have been replaced, or if the DTC C1399F0 is present, the following steps should be taken:

1. Initiate Test Plan: Technicians must use the ODIS diagnostic system (via GFF or Guided Functions) to select the "003 Brake-In Service Pads" test plan. This plan is designed to properly complete the brake pad break-in sequence.
2. Reevaluate and Release: After running the test plan, the vehicle should be reevaluated to ensure the DTC C1399F0 has cleared and that recuperation is functioning correctly. Once confirmed, the vehicle can be released.

This procedure ensures that the brake system completes its necessary break-in, allowing the recuperation system to return to normal operation.

Warranty Information

Repairs performed under Audi Technical Service Bulletin 2063679/3 are covered under warranty for up to 48 months or 50,000 miles, whichever comes first, under Claim Type 1EB. If the vehicle is outside of this warranty period, this Technical Service Bulletin serves as informational guidance, and any repairs would typically not be covered. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty. The Service Number associated with this bulletin for claim purposes is DADP.

Important Warnings

Owners should be aware that the brake application mode, which can lead to the Audi e-tron GT C1399F0 fault code, is an internal process and is not actively displayed to the customer in the instrument cluster or the MMI. The system is designed to automatically deactivate this mode and the DTC once the required amount of energy for brake pad break-in has been reached. Therefore, if you experience persistent low recuperation, it's advisable to have your vehicle inspected by an authorized Audi service center.

---

Source: NHTSA ID: 10212111, Audi Technical Service Bulletin 45 22 24 2063679/3