2021 Mercedes-Benz AMG GT Headlamp Fogging TSB

Owners of the 2021 Mercedes-Benz AMG GT may notice condensation or fogging within their headlamps or front fog lamps. This issue, described as "Headlamp or front fog lamp leaky or fogged," is addressed by Mercedes-Benz Technical Service Bulletin (TSB) L182.10-P-078301. The TSB clarifies that while some fogging is a natural phenomenon, persistent or excessive condensation may require specific attention.

Symptoms

If you own a 2021 Mercedes-Benz AMG GT, you might observe the following symptoms related to your vehicle's exterior lighting:

• "Lighting > Exterior lights > Front fog lights > Malfunction"
• "Lighting > Exterior lights > Driving lights > Main headlamps > Fogged"
• "Lighting > Exterior lights > Driving lights > Taillamp > Fogged"

These messages or visual cues indicate the presence of moisture inside the lamp units.

Understanding Headlamp Fogging

According to Mercedes-Benz, fogging of headlamps is often a natural occurrence, especially under certain climatic conditions. It typically does not indicate a technical impairment of the headlamp or affect its operation or service life. Modern headlamps are designed to comply with all applicable standards, and many feature a pressure compensation diaphragm in the housing cover, creating a "closed system" that allows for minor moisture exchange.

Important Warnings and What Not to Do

Mercedes-Benz provides specific guidance to technicians and owners regarding this condition:

• Do not perform an engine wash before attempting the defogging test described in the repair procedure.
• It is not physically possible to defog the headlamps completely. Some residual fogging is normal and does not impair the operation or service life of the headlamp.
• External damage to the headlamp/rear lamp or faulty seating of the cover caps does not present a warranty or goodwill case. This means if the fogging is due to physical damage, it may not be covered under warranty.

Clearing Condensation: Remedy 1

For 2021 Mercedes-Benz AMG GT vehicles experiencing fogged or condensed LED headlamps, LED rear lamps, or halogen/xenon headlamps, the TSB outlines a procedure to help clear the moisture:

1. Vehicle Preparation: Drive the vehicle into a workshop where the temperature is higher than +18 °C (64.4 °F). Connect the exhaust extraction system.
2. Power Management: Switch off the engine and connect a battery support device via a charger to maintain power.
3. Access: Open the hood or trunk to allow air circulation.
4. Activate Lights: Switch on the vehicle's lights.
5. Defogging Period: Leave the vehicle in this state for 60 minutes.
6. Inspection: After 60 minutes, check for condensation. A significant reduction in fogging (thawing progress) should be clearly recognizable.

If, after this procedure, there is no visible reduction in the condensation, it suggests a potential defect, and further inspection is required (see Remedy 2).

Diagnosing Damaged Headlamps: Remedy 2

If the initial defogging procedure is unsuccessful, or if the 2021 Mercedes-Benz AMG GT headlamp fogging persists, a damaged headlamp might be the cause. Technicians should perform the following checks:

1. External Inspection: Check the headlamp for any external damage. Ensure that the cover caps and the pressure compensation diaphragm are correctly seated.
2. Electrical Connections: Inspect the electrical connectors, including plugs and pins, for any issues.
3. Leak Tightness Test: Conduct a leak tightness test on the headlamp in accordance with Mercedes-Benz document LI82.10-P-078307. This test is specifically for headlamps.
4. Component Replacement: If external damage is found on the headlamp or rear lamp, the component part should be replaced following the Workshop Information System (WIS) instructions.

For headlamps that repeatedly experience fogging, it is possible to install desiccant packs to absorb moisture. The TSB also references related ventilation system documents: L182.10-P-064766 for open ventilation systems and LI82.10-P-078304 for closed ventilation systems.

Owner Action and Next Steps

If you are experiencing persistent 2021 Mercedes-Benz AMG GT headlamp fogging, it is recommended to schedule an appointment with an authorized Mercedes-Benz service center. They can perform the diagnostic and clearing procedures outlined in TSB L182.10-P-078301. While minor fogging is considered normal, a professional assessment can determine if a defect is present or if further action, such as installing desiccant packs, is necessary.

NHTSA ID: 11007753