2021 Mercedes-Benz AMG GT Headlamp Fogging TSB

Mercedes-Benz has released Technical Service Bulletin (TSB) L182.10-P-078301 to address concerns regarding headlamp and front fog lamp fogging or condensation in various models, including the 2021 Mercedes-Benz AMG GT. This TSB clarifies that such fogging is often a natural occurrence and provides a detailed procedure for addressing it.

Symptoms

Owners of affected vehicles may observe the following conditions related to the AMG GT headlamp fogging:

• "Headlamp, front fog lamp leaky or fogged"
• "Lighting > Exterior lights > Front fog lights > Malfunction"
• "Lighting > Exterior lights > Driving lights > Main headlamps > Fogged"
• "Lighting > Exterior lights > Driving lights > Taillamp > Fogged"

Diagnosis and Trigger Conditions

According to Mercedes-Benz, fogging of headlamps is a natural phenomenon that can occur under specific climatic conditions. It typically does not lead to any technical impairment of the headlamp's function or service life. The TSB outlines a two-part remedy: first, a procedure to clear existing condensation, and second, steps to identify if a damaged headlamp is contributing to persistent fogging.

Repair Procedure Summary

Remedy 1: Clearing Fogged/Condensed Headlamps and Rear Lamps

This procedure is designed to clear condensation from LED headlamps, LED rear lamps, and halogen/xenon headlamps. It involves specific environmental and vehicle conditions to be effective.

1. Drive the vehicle into a workshop where the ambient temperature is higher than +64.4°F (+18°C). Connect the exhaust extraction system.
2. Switch off the engine and connect a battery support device via a charger to maintain battery voltage.
3. Open the hood or trunk of the vehicle.
4. Switch on the vehicle's lights.
5. Leave the vehicle in this state for 60 minutes.
6. After the specified time, check for a significant reduction in condensation, indicating thawing progress.

Remedy 2: Identifying and Addressing Damaged Headlamps

If the first remedy does not significantly reduce condensation, or if the AMG GT headlamp fogging persists, a damaged headlamp may be the cause. Technicians should perform a thorough inspection:

1. Check the headlamp for any external damage and ensure that the cover caps and the pressure compensation diaphragm are correctly seated.
2. Inspect the electrical connectors, plugs, and pins for any issues.
3. Perform a leak tightness test on the headlamps in accordance with reference LI82.10-P-078896.
4. If external damage is found on the headlamp or rear lamp, the component part should be replaced following the Mercedes-Benz Workshop Information System (WIS) instructions.

For recurring headlamp fogging issues, it is possible to install desiccant packs. The TSB also references specific ventilation system documents: L182.10-P-078302 for open ventilation systems and L182.10-P-078304 for closed ventilation systems.

Important Warnings

Mercedes-Benz provides several critical notes for technicians and owners regarding this issue:

• "Do not perform an engine wash before the defogging test."
• "It is not physically possible to defog the headlamps completely. Fogging does not impair the operation or the 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 good-will case."
• The TSB explicitly states, "DO NOT assume that a symptom or condition... affects any particular vehicle... nor does it imply warranty coverage." It also clarifies, "The information contained in this document does not guarantee warranty coverage nor does it extend the vehicle's warranty in any way."

Owner Action

If you are experiencing AMG GT headlamp fogging or any of the described symptoms, it is recommended to visit an authorized Mercedes-Benz service center. They can perform the diagnostic and remedy procedures outlined in TSB L182.10-P-078301 to properly assess and address the condensation.

NHTSA ID: 11017496