2018-2025 Audi A4-A7 Damp Smell, Wet Footwell TSB 2081402

Symptoms of Moisture in the Footwell

Owners of certain 2018-2025 Audi A4, A5, A6, and A7 models may notice a distinct "musty or damp smell in the passenger compartment" or a "wet footwell in the front of the vehicle." This unpleasant odor and moisture can create an uncomfortable driving environment and, if left unaddressed, may lead to mold growth or damage to the vehicle's interior components. The presence of water can be particularly noticeable on the carpet in the front of the vehicle.

Technical Background: The Root Cause

The primary cause of the "moisture in footwell, damp smell in passenger compartment" issue, as identified in Audi Technical Service Bulletin (TSB) 2081402/1, is the incorrect installation of the drain hose for the air conditioning unit. The AC system generates condensation during operation, which is designed to drain out of the vehicle through this hose. When the drain hose is not properly positioned or secured, this condensation can instead leak into the passenger compartment. Over time, this accumulation of water leads to a wet carpet and the development of a musty odor. This condition can often be easily reproduced during a workshop diagnosis.

Repair Procedure Summary

To resolve the damp smell and wet footwell, technicians must inspect and correct the position of the air conditioning drain hose. The TSB provides specific visual guidance to ensure the correct repair is performed for various models. For example, Figure 1 in the TSB illustrates the proper assembly overview for Audi A4 and A5 models, detailing the correct routing and connection points of the drain hose. Similarly, Figure 2 provides an assembly overview specifically for Audi A6 and A7 models, highlighting where the drain hose should be correctly seated to prevent condensation from entering the cabin.

The repair process involves accessing the drain hose, verifying its current position, and then adjusting it to ensure it is securely and correctly installed, allowing for proper drainage of AC condensation outside the vehicle. The labor operation associated with this fix is identified as "Remove and install water drain hose," using service number 8791 and damage code 0018.

Important Warranty Information

For vehicles that are still covered under their original manufacturer's warranty, this repair should be performed free of charge, adhering to the guidelines outlined in the Audi Warranty Policies and Procedures Manual. However, if your vehicle falls outside of its warranty period, Technical Service Bulletin (TSB) 2081402/1 is provided as