2021 Audi A4, A5, S4, S5, RS 5 ABS Warning Light TSB

Symptoms

Owners of affected 2021 Audi models may notice an "ABS warning light on in the instrument cluster." This light indicates a potential issue with the Anti-lock Braking System, which is critical for vehicle safety.

Fault Codes / DTCs

When the 2021 Audi ABS warning light illuminates, diagnostic scans may reveal one or more of the following Diagnostic Trouble Codes (DTCs) stored in the ABS control module (J104, address word 0003):

Code	Description
C050200	front left wheel speed sensor Short circuit to ground
C050800	front right wheel speed sensor Short circuit to ground

Diagnosis and Technical Background

The root cause for these DTCs and the illuminated 2021 Audi ABS warning light is often an improperly crimped wire in the front wheel speed sensor connector. This poor connection can lead to a short circuit, triggering the fault codes.

Audi has implemented an improved crimping process for the wheel speed and brake pad harness in production to prevent this issue in newer vehicles.

Important Warnings

Technicians should note that if the wire is found to be properly crimped during diagnosis, this Technical Service Bulletin 2061331/1 does not apply. In such cases, further normal diagnostic procedures should be followed to identify the underlying cause of the ABS warning light.

Repair Procedure Summary

If the front wheel speed sensor wiring is found to be improperly crimped, the repair involves replacing the affected harness. The general steps are:

1. Inspect Wiring: Visually check the front wheel speed sensor wiring to determine if the wire strands are protruding past the crimp sleeve. Figure 1 in the TSB shows a properly crimped wire, while Figure 2 illustrates an improperly crimped wire.
2. Harness Replacement: If an improperly crimped wire is identified, the affected harness for the front speed sensor and brake pad wear indicator must be replaced.
3. Part Identification: Technicians should use ETKA illustration 927-010 to correctly identify the specific harness needed for replacement.

Required Tools or Parts

Technicians should consult ETKA and their Parts Department for the most current information regarding necessary fasteners, bolts, nuts, screws, and the specific repair kit for the front speed sensor and brake pad wear indicator. The repair kit is typically required if an improperly crimped wire is found.

Warranty Information

This repair, outlined in Technical Service Bulletin 2061331/1, may be covered under warranty. The applicable claim types are:

• Type 110: For vehicles up to 48 months or 50,000 miles.
• Type G10: For Audi Certified Pre-Owned (CPO) vehicles, requiring owner verification.

If the vehicle is outside of warranty coverage, this bulletin serves as informational guidance only. The Service Numbers are 9715 for the left side and 9716 for the right side, with a Damage Code of 0021 for either side. Labor operations include removing and installing the wheel, front wheel arch liner, checking the wiring harness, and removing/installing the front wiring harness, with specific labor units (TU) assigned to each task. Diagnostic time is also covered, and road tests are included before and after the service procedure.

All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty.

What Owners Should Do

If your 2021 Audi A4, A5, S4, S5, or RS 5 displays an "ABS warning light on in the instrument cluster" or if you suspect an issue related to the front wheel speed sensors, it is recommended to schedule an appointment with an authorized Audi service center. They can perform a diagnostic scan to confirm the presence of DTCs C050200 or C050800 and carry out the necessary inspection and repair as described in this Technical Service Bulletin.

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Source: NHTSA ID: 10183457