2021-2022 Audi A4/A5/S4/S5/RS5 Rear Brake Caliper Leak TSB

Symptoms

Owners of certain 2021-2022 Audi A4, A5, S4, S5, and RS 5 models might observe moisture or contamination on one of the rear brake calipers. This can sometimes be accompanied by a "warning lamp indicate that there is a leak in the brake system" message on the instrument cluster. The workshop findings confirm that moisture is indeed identified on one of the rear brake calipers when inspected.

Technical Background

Audi's TSB 47 22 11 2067117/1 explains that the presence of moisture on a rear brake caliper does not automatically mean there is a leak. During the assembly process, a specific assembly fluid is used by the supplier. Residue from this fluid can remain on the components, leading to visible moisture. Therefore, what appears to be an Audi rear brake caliper leak might simply be this harmless residue.

Diagnosis and Repair Procedure Summary

When a customer reports a potential Audi rear brake caliper leak or a brake system warning, technicians should follow a specific diagnostic process outlined in TSB 47 22 11 2067117/1. The procedure involves:

1. Cleaning the Area: The first step is to thoroughly clean the affected area around the rear brake caliper.
2. Inspection: After cleaning, the technician must carefully check for any moisture underneath the protective sleeve of the caliper. A visual reference (Figure 1 in the original TSB) shows what a dry state should look like.
3. Reassessment: If no moisture is found underneath the protective sleeve after cleaning, the initial complaint should be reassessed. This indicates that the visible moisture was likely production residue. In such cases, the technician should continue to evaluate the rest of the brake system to rule out any other potential issues.

This TSB highlights that visible moisture alone is not conclusive evidence of a brake fluid leak and guides technicians to perform a more detailed inspection to differentiate between assembly fluid residue and an actual problem.

Important Information for Owners

It is crucial for owners to understand that this Technical Service Bulletin is for informational purposes only. It is not applicable to any Audi Warranty. This means that any diagnostic work or potential repairs related to this issue may not be covered under your vehicle's warranty. If you notice moisture on your rear brake caliper or a brake system warning light, it is advisable to have your vehicle inspected by an authorized Audi service center to determine the exact cause.

Production Improvements

Audi implemented production improvements starting in May 2022 to address the potential for assembly fluid residue. This suggests that newer vehicles might be less prone to exhibiting this specific condition.

Source: NHTSA ID: 10212114