2016-2024 Audi Exterior Light Moisture Accumulation TSB

Audi Technical Service Bulletin (TSB) 2012749/16, last revised on May 9, 2023, addresses concerns regarding moisture accumulation in the exterior lights of various Audi models from 2016 through 2024. This TSB provides crucial information for owners and technicians to differentiate between normal, expected condensation and actual defects. Understanding the conditions that lead to Audi exterior light moisture can prevent unnecessary repairs and clarify warranty coverage.

Symptoms of Exterior Light Moisture

Owners may observe the following symptoms related to Audi exterior light moisture:

• Condensation visible on the inside of the headlight lens.
• Moisture present inside the taillight, fog light, side marker light, or front turn signal lenses.
• Condensation within the daytime running lights or the third brake light lens.

Technical Background: Why Condensation Occurs

Exterior lights in Audi vehicles are designed as "open systems," meaning air from the outside circulates through the component. This design is essential for pressure equalization, preventing damage from changes in air pressure.

Condensation typically forms in winter or wet weather when there is high humidity. When the vehicle is parked after use, residual heat from the engine warms the back of the headlight, while the lens cools from the outside air. This temperature difference causes humidity in the air to condense on the inside of the lens.

Driving through a car wash or using a steam cleaner can amplify this phenomenon by increasing humidity within the light component. LED headlights and taillights, which do not produce infrared heat, rely solely on airflow from driving to clear condensation.

Important Warnings for Owners

• The normal presence of moisture/condensation is NOT a condition covered under warranty. Parts replacement will not correct normal condensation, and the customer will likely still experience the same issue.
• Leaving a vehicle stationary with lamps on is NOT sufficient for clearing moisture.
• If a warranty claim is submitted for abnormal moisture, photos must be uploaded to DOC-IT for review. Claims submitted without photos may be charged back.

Differentiating Normal from Abnormal Moisture

Normal amounts of moisture/condensation:

• Does not affect the performance of the headlight or taillight.
• Does not cause corrosion inside the component.
• Can occur on any lamp and may vary depending on environmental conditions and driving habits.
• The light emission surface (Figure 2A) of the main beam should clear after driving for approximately 10 minutes with the main beam on, at speeds consistently over 45 mph. Residual condensation (Figure 2B) may still be present on other internal surfaces, which is considered normal.

Abnormal amounts of moisture:

• Water drops or condensation remain on the light emission surface (Figure 2A) even after performing the prescribed test drive (10 minutes, >45 mph, main beam on).
• Examples of excessive moisture still present after a thorough test drive are shown in Figure 3 (headlamp) and Figure 4 (tail lamps).

Diagnosis and Inspection

To determine if the Audi exterior light moisture is normal or abnormal, perform the following test:

1. Drive the vehicle for approximately 10 minutes with the main beam on.
2. Maintain driving speeds consistently over 45 mph to ensure proper ventilation of the light assembly.

After this test, if water drops or condensation are still present on the light emission surface (Figure 2A), inspect the headlamp assembly for the following root causes:

• Missing cover.
• Damaged seal.
• Clogged drain.
• Outside influence.
• Vent tube disconnected from the headlamp.

Technicians are advised to take photos before and after this diagnostic step for visual comparison and to retain them for at least one month after claim submission. Proper documentation of optical concerns for headlights and tail lights should follow the instructions in TSB 2061922.

Warranty Information

This Technical Service Bulletin (TSB 2012749/16) is informational only and is not applicable to any Audi warranty. As stated, normal moisture accumulation is not a warrantable condition. Warranty coverage would only apply if an abnormal condition is identified and linked to a specific defect covered under the vehicle's warranty.

Revision History

This TSB, 94 23 64 2012749/16, was issued on May 9, 2023. It supersedes Technical Service Bulletin Group 94 number 21-34, dated February 17, 2021. Previous revisions include:

• Revision 16 (May 9, 2023): Revised header (Added MY 23,24).
• Revision 15 (February 17, 2021): Revised header (Added MY22, models, and attachment), Revised Service (Added reference to TSB 2061922).
• Revision 14 (December 6, 2019): Revised header (Added MY20 and MY21).

All part and service references provided in this TSB (2012749) are subject to change and/or removal. Always check with your Parts Department and/or ETKA for the latest information and parts bulletins.

NHTSA ID: 10237731