Mercedes W166 Brake Light Rear Third Additional Stop Lamp A1668200056

Visual condition of the part 

The product shows signs of use visible in the photos. 

Mercedes W166 Brake Light Rear Third Additional Stop Lamp is an original component from the Main and center brake lights group, designed for installation in the rear part of the vehicle body. It provides clear, highly visible braking signaling, improving the readability of light signals for drivers behind you. This is a practical solution for users who want to restore full functionality to the lighting system in their Mercedes W166.

Specifications and technical data

• SKU: A1668200056-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1668200056
• Substitutable numbers: A1668200056, A 166 820 00 56
• Location on the vehicle: Rear
• Category: Centre & Third Brake Light Assemblies

Purpose and function of the third brake light

The presented third additional brake light is mounted in the rear area of the vehicle, where it is responsible for additional, centrally positioned braking signaling. Thanks to its elevated position relative to the main brake lights, it increases signal readability, especially in heavy city traffic and when driving in adverse weather conditions.

This component works with the factory electrical system of the Mercedes, which allows for consistent operation of all brake lights. An additional light source on the vehicle's axis improves passive safety, helping other road users react faster to braking.

Benefits of using an original Mercedes brake light

Using an original third brake light in a Mercedes W166 allows you to maintain factory lighting parameters and the aesthetics of the rear bodywork. The shape, mounting method, and lens geometry are matched to the body lines, allowing the component to integrate well with the trunk lid or the upper part of the rear window (depending on the body version).

The main advantages of this solution include:

• Factory fit – no need for modifications to the installation or mounts.
• Consistent appearance with other Mercedes W166 lighting elements.
• Stable operation within the vehicle's original electrical system.
• Properly selected lighting characteristics, improving the visibility of the braking signal.

Installation and operational characteristics

The third additional brake light is intended for installation in the rear zone of the body, in the location provided by the vehicle manufacturer. Thanks to its factory design, the installation process is straightforward – the component works with the original mounting points and wiring harness, which reduces the risk of leaks or looseness.

In daily use, a properly functioning additional brake light:

• increases the readability of the braking signal for vehicles driving higher up (e.g., SUVs, vans),
• improves vehicle visibility during sudden braking,
• supports even distribution of the light signal in the rear part of the car.

Condition of the component and use in vehicle service

The offered third brake light is a secondary market component, making it an attractive solution for post-accident repairs, replacing a damaged lens, or restoring full efficiency to the lighting system. It is a practical option for users who want to maintain the original design of the lighting system in their Mercedes W166 while optimizing service costs.

It is always worth confirming the selection of the correct component based on vehicle documentation or identification data to ensure full compatibility with the specific equipment version and model year.

If you are planning a comprehensive repair or upgrade of the rear lighting zone in your Mercedes and need other elements from the same group, such as main brake lights, central light modules, or additional lamps in the trunk lid, check the available parts in the Mercedes main and center brake lights category.

For drivers interested in learning more about selecting secondary market parts, compatibility rules, and verifying manufacturer markings, a guide in the form of a technical article may be helpful – check out the material BMW B58 code – checklist before buying a turbocharger and intercooler, which shows step-by-step how to approach component selection based on technical data and OEM markings.