BMW 3 Series E90 E91 E92 325D M57N2 Diesel Automatic Engine Wiring Loom Harness

Description

BMW 3 Series E90 E91 E92 325D M57N2 Diesel Automatic Engine Wiring Loom Harness is an original component from the Cables, wiring looms and connectors group, designed for use with the M57N2 diesel engine and automatic transmission. It ensures a stable electrical connection between sensors, engine peripherals, and the ECU, which translates into predictable powertrain operation.

Specifications and technical data

• SKU: rhd-7801103
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 7801103
• Substitutable numbers: 12517811807, 7811807, 12517804834, 7804834, 12517801103, 7801103
• Fuel type: Diesel
• Gearbox type: Automatic
• Category: Wiring Harnesses, Cables & Connectors

Purpose and function in the powertrain

This engine wiring loom is specifically designed for BMW 3 Series E90, E91, and E92 models in the 325D version with the M57N2 diesel engine, paired with an automatic transmission. It is responsible for transmitting signals between key peripheral components, such as sensors, control valves, or actuators, and the engine control unit.

Thanks to its dedicated fitment for the specific Diesel + automatic transmission powertrain configuration, the wiring loom maintains factory control logic without the need for modifications or adaptations from other engine versions.

Construction and advantages of the original BMW wiring loom

The original BMW engine wiring loom has been developed for resistance to temperature, vibration, and the harsh conditions of the engine bay. The connectors and wire gauges used are selected to ensure stable power supply and precise transmission of measurement and control signals.

Key benefits of using a factory wiring loom include:

• secure fitment to the M57N2 engine and factory peripherals,
• preservation of original mounting points and wire routing,
• compatibility with the factory engine ECU and automatic transmission control,
• reduction of the risk of electrical faults resulting from improper wiring modifications.

Choosing an original wiring loom from the Cables, wiring looms and connectors group helps maintain the integrity of the entire electrical system within the powertrain.

Application in diagnostics, repair, and modernization

The BMW 3 Series E90 E91 E92 325D M57N2 Diesel Automatic Engine Wiring Loom Harness is particularly useful in situations where the existing installation has suffered mechanical, thermal, or corrosion damage, as well as after unprofessional electrical modifications. Replacing the complete wiring loom is often a faster and more predictable solution than point-repairs of multiple wire sections.

This component is suitable for both standard repairs and comprehensive powertrain rebuilding after a collision, engine bay fire, or long-term operation in difficult conditions. Factory connectors and wire lengths facilitate plug-and-play installation, which reduces workshop labor time and minimizes the risk of assembly errors.

Characteristics of the used OEM part

The offered wiring loom is a used part, sourced from dismantling, which allows combining the advantages of original manufacturing with an attractive price compared to a new component. For many users and workshops, this is a reasonable compromise between quality and repair costs, especially in the case of older BMW 3 Series generations.

If you want to better understand why original second-hand parts are often a better choice than new aftermarket replacements, check out our practical guide: 5 reasons why a used OEM part is a better choice than a replacement.

Complementary BMW engine installation components

If you are planning a comprehensive repair or modernization of the engine area in your BMW and need other elements from the same group, such as additional wiring looms, wire sections, or service connectors, check out the available parts in the BMW cables, wiring looms and connectors category.