Fitment

Compatible with Audi diesel vehicles equipped with V6/V8 TDI engines and SCR (Selective Catalytic Reduction) emission systems.

Common applications include Audi large-platform diesel models using this NOx sensor configuration:

• Audi A8 (D4 / 4H chassis) 3.0 TDI / 4.2 TDI
• Audi Q7 (4L platform variants depending on engine code)
• Volkswagen Group premium diesel platforms with SCR/AdBlue systems

Fitment depends strongly on engine code (e.g., CTBA / CTBD / similar VAG diesel variants) and ECU calibration.

Technical Description

This NOx sensor is installed in the diesel exhaust system to measure nitrogen oxide (NOx) concentration in real time.

It communicates with the ECU to regulate SCR system dosing (AdBlue/urea injection) and ensure compliance with diesel emission standards.

The sensor assembly typically includes an integrated control module and is mounted in the exhaust stream before or after the SCR catalyst depending on configuration.

Symptoms / Fault Codes

Common symptoms of failure include:

• Check engine light
• P2200 / P229F fault codes (system dependent)
• SCR / AdBlue system warning
• Reduced engine power or limp mode
• Increased emissions and fuel consumption

OE / Part Numbers

• 4H0907807D
• 5WK96797A (Continental reference)
• 8K0 / 4M / related platform cross-references may exist depending on revision

FAQ

What does this NOx sensor do?

It measures nitrogen oxide levels in diesel exhaust gases and sends data to the ECU to control SCR emission system operation.

Where is it used?

It is used in Audi large diesel platforms such as A8 and Q7 equipped with SCR/AdBlue emission systems.

Are 4H0907807D sensors interchangeable with similar part numbers?

Not always. Even if connectors and housings look similar, compatibility depends on ECU software calibration and exact OE matching.

What happens if it fails?

It may trigger emission warnings, fault codes, and reduced engine performance depending on SCR system strategy.