NTK 24308 Air / Fuel Ratio Sensor - Upstream, Upstream Left or Upstream Right

NTK Direct Fit Air/Fuel Ratio Sensor

NTK Part Number 24308 is a direct-fit heated air/fuel ratio sensor built for specific upstream applications. It uses a 5-wire design with an 18.000 mm thread diameter and a 23.5 in. wiring harness length for OE-style replacement on select Audi models.

NTK’s Direct Fit 5-Wire A/F Sensor line is engineered for import and domestic coverage with application-specific fit, form, and function. As an OE sensor manufacturer, NTK applies ceramic manufacturing expertise and production testing to support consistent signal performance and reliable emissions-system operation.

Key Features

• Direct-fit air/fuel ratio sensor for specific upstream locations
• Heated sensor design for faster operating temperature
• 5-wire configuration for OE-style signal control
• 23.5 in. wiring harness length
• 18.000 mm thread diameter with 0.38 in. thread length
• Specific fit for select Audi A4, A4 Quattro, A5 Quattro, A6, A6 Quattro, and Q5 applications
• Mounting bracket not included

Detailed Description

NTK 24308 is a direct replacement air/fuel ratio sensor for upstream positions on select Audi vehicles, including 2005-2010 Audi A4, A4 Quattro, A5 Quattro, A6, A6 Quattro, and Q5 applications. It is listed for upstream right, upstream left, and upstream locations depending on the vehicle and engine configuration, making it a strong match for buyers searching for an Audi A4 upstream oxygen sensor, Audi A6 bank 1 sensor 1 replacement, or Audi Q5 upstream air/fuel ratio sensor. This part cross-references Bosch 18089 for the same application.

Built by NTK, the sensor specialist and a major OE oxygen sensor supplier, this unit is manufactured with ceramic-based sensor technology and tested during production to help maintain quality and reliability that meet or exceed OE specifications. Part number 24308 is intended for direct-fit replacement where the original sensor uses a 5-wire heated design and specific mounting/thread dimensions.

Common Issues This Sensor May Resolve

• Check engine light related to upstream air/fuel ratio or oxygen sensor faults
• Rough idle or inconsistent fuel trim readings
• Poor fuel economy caused by inaccurate exhaust feedback
• Emissions test failure tied to sensor performance
• Slow sensor response or heater circuit-related diagnostic trouble codes

Installation Notes and Tips

Verify the vehicle’s year, engine, and sensor position before ordering, since fitment varies by Audi model and upstream location. Confirm the connector, thread size, and harness length match the original sensor, and inspect the exhaust bung threads before installation. Use the vehicle’s service information for torque and routing details, and clear diagnostic codes after installation if required.

Quality Assurance

NTK manufactures oxygen and air/fuel ratio sensors with OE-focused application coverage and production testing for fit, form, and function. Part number 24308 is built to support direct replacement on confirmed Audi applications, including 2005-2010 Audi A4 and A4 Quattro, 2005-2008 Audi A6 Quattro, and related upstream positions.