Mercedes-Benz C-Class W203 C 180 200 K 230 M111 Coolant Thermostat A1112030975

Mercedes-Benz C-Class W203 C 180 200 K 230 M111 Coolant Thermostat is a cooling system component designed for M111 series engines in the C-Class W203 model. It is responsible for precise control of the coolant circulation, which translates into a stable operating temperature of the power unit and proper engine performance. Thanks to the use of the original Mercedes design, the part ensures factory-fit to the cooling system without the need for any modifications.

Specifications and technical data

• SKU: A1112001715
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A1112001303
• Substitutable numbers: A1112001715, A 111 200 17 15, A1112030975, A 111 203 09 75, BG
• Category: Thermostats & Housings

Purpose and function in the cooling system

The thermostat housing in the M111 engine is responsible for directing the flow of coolant between the small and large circuits. A properly functioning thermostat allows the engine to reach operating temperature faster and then maintain it, which reduces fuel consumption and lowers the mechanical load on the power unit. For Mercedes W203 C 180, C 200, and C 230 models, this is a key component for maintaining proper engine performance characteristics in both city and highway driving.

Construction and fitment for Mercedes W203

The presented thermostat housing has been designed specifically for the cooling system of M111 engines in the W203 body, ensuring:

• proper positioning relative to the engine block and cooling hoses,
• correct routing of fluid flow channels,
• compatibility with factory connectors and mounts.

Such a fit reduces the risk of leaks and facilitates installation in workshop conditions. For a mechanic, this means efficient replacement, and for the user – stable operation of the cooling system without the need for additional adaptations.

Characteristics of the used component

The item comes from disassembly, which in practice means that it is a used part that retains the functionality required for daily operation. In the case of thermostat housings for Mercedes, it is important that the body is airtight and the contact surfaces for gaskets are suitable for reassembly. Choosing such a component is a reasonable compromise between repair costs and maintaining the manufacturer's original design.

Benefits of using an original thermostat housing

Using a thermostat housing dedicated to the M111 engine in a Mercedes W203 brings a number of practical benefits:

• Factory fit – no problems with geometry, bolt spacing, or connector diameters.
• Consistency with other cooling system components – hoses, radiator, and pump operate under the conditions intended by the manufacturer.
• Reduction of the risk of engine overheating or undercooling, which affects the durability of the power unit.
• Possibility of economical repair while maintaining the original technical specification.

Mercedes thermostats and housings – expansion and cooling system service

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other components from the same group, such as additional housings, bodies, or fluid flow control elements, check out the available parts in the Mercedes thermostats and housings category.

More about the cost-effectiveness of used parts

If you are interested in the broader economic context of using second-hand parts and want to better understand when used components are a reasonable service choice, it is worth reading our guide: Smart Skoda servicing – why second-hand parts are the best choice for your wallet. Although it concerns a different brand, it well illustrates how to consciously approach the purchase of used components in the automotive industry.