Bosch 17178 Oxygen Sensor - Upstream, Upstream Left or Upstream Right

Bosch Wideband OE Oxygen Sensor

Bosch 17178 is an Actual OE wideband oxygen sensor built for precise air-fuel ratio measurement across the full lambda range. It uses a heated, wide-band design with a 5-wire harness and 6-terminal blade connection to deliver fast response and stable feedback to the ECU.

Compatible With Audi A4, A5, A6, Q5, Q7, R8, S6, S8, TT Quattro, A3 Quattro, A4 allroad, A4 Quattro, A6 Quattro, allroad, and Volkswagen Passat, CC, Passat CC, Touareg, Eos, R32, plus Porsche Cayenne upstream applications. Bosch 17178 is also a direct-fit choice for drivers searching for an upstream wideband oxygen sensor for Audi Q7 or Volkswagen Touareg OE replacement service.

• Wide-band oxygen sensor for continuous air-fuel ratio monitoring
• Heated design for faster light-off and stable operation
• Specific-fit sensor with included wiring harness
• Threaded mounting with 18 mm thread diameter and 22 mm hex size
• Metal housing built for high-temperature exhaust environments
• Oblong male connector with blade terminals

OE-Style Wideband Control

Bosch pioneered the wideband A/F oxygen sensor design, and part number 17178 reflects that OE development history in a modern replacement sensor. It provides detailed feedback to the engine control unit so fuel delivery can be managed more accurately than with a traditional switching sensor. That makes it a strong match for upstream sensor service on Audi and Volkswagen platforms where precise mixture control matters for drivability, emissions, and fuel economy.

This part cross-references 1K0998262K and 958906262A for the same application.

Common Problems This Sensor Can Address

• Check engine light related to oxygen sensor performance
• Incorrect air-fuel ratio readings from a worn upstream sensor
• Rough idle or hesitation caused by inaccurate exhaust feedback
• Reduced fuel economy from poor mixture control
• Emissions test failures tied to sensor response issues

Installation Notes

Verify the connector style, wire count, and upstream position before installation. This Bosch 17178 sensor is a specific-fit replacement with a 26.2-inch wiring harness length and 28.3-inch sealing-surface-to-connector length. Use the correct oxygen sensor socket for the 22 mm hex, and confirm the 18 mm thread size matches the original sensor location.

Fits 2006-2010 Audi A4, upstream; fits 2009-2016 Audi A4 Quattro, upstream; fits 2011-2017 Audi Q5, upstream; fits 2011-2017 Volkswagen Touareg, upstream; fits 2008-2014 Porsche Cayenne, upstream.

Quality Assurance

Bosch supplies this Actual OE Oxygen Sensor with OE-proven engineering and durable ceramic construction for consistent performance under thermal cycling and load changes. The wideband design, optimized heater control, and robust build reflect Bosch’s long-standing OE development in engine management and emissions control.