Mercedes-Benz A B W169 W245 OM640 CDI Glow Plug Relay Unit Module A6401532779

Mercedes-Benz A B W169 W245 OM640 CDI Glow Plug Relay Unit Module is a specialized component of the starting system, responsible for precise control of the glow plugs in a diesel engine. Thanks to its factory design intended for the OM640 CDI unit, it ensures stable heating of the combustion chambers and more reliable starting in low temperatures. This solution helps maintain proper engine operating characteristics and reduces the risk of starting issues.

Specifications and technical data

• SKU: A6401532779
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6401532779
• Substitutable numbers: A6401532779, A 640 153 27 79, A6401530479, A 640 153 04 79, KD
• Category: Glow Plugs

Purpose and function of the glow plug module

The glow plug module in a diesel system acts as an electronic controller that manages the timing and intensity of the glow plugs. In the case of the OM640 CDI unit, the use of a dedicated module allows for:

• precise adjustment of glow parameters to the engine's operating map,
• reduction of electrical loads on the system,
• lower exhaust emissions during the startup and warm-up phase,
• increased durability of the glow plugs themselves.

As a result, the starting system remains stable, and the engine reaches its operating temperature in a predictable and repeatable manner.

Benefits of using an original module in a Mercedes

Using a glow plug module matched to the W169 and W245 series with the OM640 CDI engine translates into a number of practical operational benefits. A properly selected component:

• maintains proper cooperation with the vehicle's factory electronics,
• minimizes the risk of engine control unit errors related to the glow system,
• ensures repeatable starting parameters in various weather conditions,
• allows for maintaining the integrity of the installation without the need for harness modifications.

For the user, this means more predictable vehicle behavior on a daily basis and a lower risk of sudden starting problems in low temperatures. Combined with properly selected glow plugs, the module is an important element affecting the comfort of using a diesel car.

Product characteristics and fitment

The offered module belongs to the group of parts defined as Glow plugs, which in practice means it is an integral part of the combustion chamber heating system. Its design is prepared for cooperation with the OM640 CDI engine used in Mercedes compact class models, such as the W169 and W245. This makes it possible to maintain factory control logic without the need for adaptation or modification of the installation.

The product comes from the Mercedes brand, which in the context of glow system electronics is significant for compatibility with the engine control software and proper communication with the vehicle's network. For workshops and users, this means easier diagnostics and predictable module behavior in the long term.

Condition, service application, and practical tips

The module is offered as a used part, which makes it an attractive cost-effective alternative for repairs of the glow system in older Mercedes vehicles. This type of solution is often chosen in situations where:

• the existing module generates errors related to the glow plug circuit,
• there are cold start problems despite functional glow plugs,
• replacement of the controller is necessary after thermal or electrical damage.

During installation, it is recommended to pay attention to the condition of the connectors, proper seating in the harness, and verification of the installation for any potential short circuits. After replacement, it is worth performing computer diagnostics to confirm proper communication between the module and the engine control system.

If you are planning a comprehensive repair or upgrade of the engine area in your Mercedes and need other elements from the same group, such as glow plug controllers, glow relays, or power harnesses, check the available parts in the Mercedes Glow plugs category.

More about choosing used electronics

When selecting a used glow plug module, it is worth knowing the basic principles of evaluating automotive electronics to consciously decide when such a choice is technically and economically justified. Practical tips regarding the selection of controllers, modules, and sensors can be found in the article: The second life of electronics – when is it worth choosing used engine controllers, comfort modules, and parking sensors?.