2016-2026 Audi Exterior Light Moisture Accumulation TSB

Audi has released Technical Service Bulletin (TSB) 94 24 73 2012749/17 to address customer concerns regarding Audi exterior lights moisture accumulation. This TSB, applicable to all Audi vehicles from model years 2016 to 2026, clarifies the difference between normal condensation and abnormal moisture issues in exterior lighting components.

This bulletin provides guidance for technicians on how to diagnose and address instances of moisture inside headlights, taillights, fog lights, side marker lights, front turn signals, daytime running lights, and third brake light lenses.

Symptoms of Exterior Light Moisture

Owners may observe visible condensation or moisture on the inside of various exterior light lenses. This can include:

• Headlights
• Taillights
• Fog lights
• Side marker lights
• Front turn signals
• Daytime running lights
• Third brake light lens

Important Warnings for Owners

Audi TSB 94 24 73 2012749/17 includes several critical points for owners to understand regarding Audi exterior lights moisture:

• Normal condensation is NOT a condition covered under warranty. This means that if the moisture is determined to be normal, repair costs will not be covered.
• Parts replacement will not correct the concern and the customer will likely still experience the same issue if the moisture is normal condensation. Replacing components unnecessarily will not resolve the underlying environmental factors.
• Leaving a vehicle stationary with lamps on is NOT sufficient for clearing moisture. The ventilation system requires vehicle movement to effectively clear condensation.

Understanding Normal Condensation

Exterior lights on Audi vehicles are designed as open systems, allowing outside air to circulate for pressure equalization. This design is necessary to prevent damage from pressure differences. In certain conditions, such as winter or wet weather, humidity in the air can lead to condensation inside the lenses. This phenomenon is often described by owners as "condensation on the lens, moisture in the lamp."

Condensation typically occurs when the vehicle is parked after use. Residual heat from the engine warms the back of the headlight, while the outside air cools the lens, creating a temperature difference that causes humidity to condense on the inner surface. Driving through a car wash or using a steam cleaner can also increase humidity within the component.

Normal amounts of moisture or condensation:

• Does not affect the performance of the headlight or taillight.
• Does not cause corrosion inside the component.
• Can occur on any lamp.
• May vary depending on environmental conditions and driving habits.

Diagnosing Abnormal Moisture Issues

To determine if the Audi exterior lights moisture is abnormal, a specific diagnostic procedure is outlined. This involves a test drive to allow the vehicle's ventilation system to clear any normal condensation. Technicians are instructed to use a "Checklist" and "Flowchart" (referenced in the TSB's attachments) to guide their diagnosis.

During the test drive, the main beam of the affected light should be on. The vehicle must be driven consistently over 45 mph for approximately 10 minutes to ensure proper ventilation. After this test drive, the light emission surface (Figure 4A in the TSB) should be clear.

If water drops or condensation remain on the light emission surface after performing the test drive, it indicates an abnormal amount of moisture. In such cases, the headlamp assembly must be inspected for a root cause, which could include:

• A missing cover
• A damaged seal
• A clogged drain
• Outside influence
• A disconnected vent tube from the headlamp

Technicians are required to take photos before and after the initial diagnostic step for visual comparison and retain them for at least one month after claim submission.

Repair Procedure Summary

For abnormal moisture conditions, the repair procedure involves identifying and rectifying the root cause, such as replacing a missing cover or repairing a damaged seal. The TSB emphasizes that simply replacing parts without addressing the underlying cause will not resolve the issue if the moisture is normal condensation.

Technicians are also directed to follow instructions in TSB 2061922, titled "94 How to properly document optical concerns for headlights and taillights," for proper repair documentation.

Revision History of TSB 94 24 73 2012749/17

This Technical Service Bulletin has undergone several revisions to include additional model years and update diagnostic information:

• Revision 17 (March 9, 2024): Updated to include MY25 vehicles, revised attachments (checklist and flowchart), and updated service verbiage and steps.
• Revision 16 (May 9, 2023): Updated to include MY23 and MY24 vehicles, and provided updated technical background information.
• Revision 15 (February 17, 2021): Updated to include MY22 vehicles and attachments, and added a reference to TSB 2061922. This bulletin supersedes Technical Service Bulletin Group 94 number 23-64, dated May 9, 2023.

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Source: NHTSA ID: 10251666