Audi A4 B9 A5 F5 AdBlue Tank Reducing Agent Quality Sensor Diesel 4M0131940C

Audi A4 B9 A5 F5 AdBlue Tank Reducing Agent Quality Sensor Diesel is a specialized power supply system component designed for diesel engines, responsible for precise monitoring of AdBlue solution parameters. Thanks to its factory-engineered design for the Audi brand, it ensures seamless integration with the vehicle's electronics and stable operation of the exhaust emission reduction system. It is a practical choice for users seeking a technically matched component for modern diesel units.

Specifications and technical data

• SKU: 4M0131940C
• Mark: Audi
• Condition: Used
• OEM Part Number: 4M0131940C
• Substitutable numbers: 4M0131940C, 4M0 131 940 C
• Fuel type: Diesel
• Part type: Sensor
• Category: Air Intake & Fuel Sensors

Purpose and function in the AdBlue system

The AdBlue quality sensor in Audi A4 B9 and A5 F5 models operates within the exhaust treatment system, monitoring the parameters of the solution used in SCR technology for Diesel engines. Proper operation of this component allows the engine control unit to:

• monitor the quality and parameters of the AdBlue agent,
• adjust the injection dosage to current operating conditions,
• maintain compliance with exhaust emission standards,
• reduce the risk of the engine entering limp mode. Using the correct sensor in this part of the system has a direct impact on the stability of the exhaust treatment system and prevents AdBlue-related errors in the control unit's memory.

Compatibility with Audi diesel vehicles

The presented sensor has been designed for Audi A4 B9 generation and Audi A5 F5 generation platforms equipped with diesel engines. This means its electrical and mechanical characteristics are adapted to the wiring architecture of these models, facilitating installation and integration with the factory wiring. In practice, this translates to:

• consistent operation with the original engine control unit software,
• accurate AdBlue parameter readings in diagnostics,
• preservation of factory emission reduction system operating strategies.

Performance characteristics and installation benefits

The AdBlue quality sensor belongs to the Air and fuel intake sensors group, which are components that work directly with the fuel supply and exhaust treatment systems. Its proper operation supports:

• stable operation of the SCR system in the diesel engine,
• reduction of the risk of AdBlue error messages appearing on the dashboard,
• maintenance of optimal combustion and emission parameters. Replacing a faulty sensor with a functional unit of this type is often a key step in diagnosing AdBlue system issues, such as power limitation, forced countdown to start-up lockout, or recurring agent quality errors.

Component condition and practical aspects

The offered sensor comes from the used components group, which allows for an economical restoration of the AdBlue system's efficiency while maintaining the original design specifications. This type of solution is particularly beneficial for modern diesel units, where new exhaust treatment system components can generate high service costs. Before installation, a standard diagnostic procedure and verification of compatibility by OEM number and vehicle configuration are recommended to ensure full compatibility with the specific engine version and model year.

Technical support and selecting used electronics

When selecting sensors and other electronic components for modern diesel systems, it is worth using procedures based on OEM numbers, equipment configuration, and diagnostic data. A detailed discussion of selection principles, hardware and software compatibility issues, and practical examples can be found in the Global Parts guide: Used automotive electronics – ECU modules and second-hand sensors. If you are planning a comprehensive repair or upgrade of the fuel supply and exhaust treatment area in your Audi and need other elements from the same group, such as pressure sensors, temperature sensors, or measuring elements in the intake system, check the available parts in the Audi air and fuel intake sensors category. Additional tips on which used components in German cars are worth choosing and when it is better to opt for other solutions are provided in the article: Renovation and repair of German cars – which used parts are worth buying.