Fitment

Fits for:

• Audi A6 (C7 / 4G)
• Audi A7 (4G8)
• Audi A4 / A5 (2.0 TDI / 3.0 TDI variants depending on engine code)
• Audi Q5 / Q7 diesel SCR applications
• Volkswagen Touareg (shared VAG diesel SCR platform)
• Engine: VAG 2.0 / 3.0 TDI diesel engines with SCR (AdBlue / DEF) system
• Position: Exhaust NOx sensor (SCR inlet or outlet depending on configuration)
• OE / Cross References: 4G0907807S / 4G0 907 807 S / SNS451 / A2C39689500-01 / 5WK97212 / 8W0907807E / 4K0907807 / 4G0907807AC / 4G0907807L / 70680085 / 197490 / V10-72-0312 / CASCO CSN73B98AS / VAG NOx sensor family

FAQ

Q1: Are 4G0907807S and SNS451 the same sensor?
A1: Yes. 4G0907807S is the VAG OE number, and SNS451 is the corresponding NOx sensor reference used in Audi/VW SCR diesel systems.

Q2: What vehicles use this sensor?
A2: It is commonly used on Audi A6, A7, Q5, Q7 and Volkswagen Touareg diesel models with Euro 6 SCR (AdBlue) systems.

Q3: Is this inlet or outlet sensor?
A3: It can be used as either upstream (before SCR catalyst) or downstream (after SCR catalyst) depending on exhaust system layout.

Q4: What does this sensor do?
A4: It measures nitrogen oxide (NOx) levels in exhaust gases and sends data to the ECU, which controls AdBlue dosing to reduce emissions and maintain SCR efficiency.