Denso 234-4991 Oxygen Sensor - Downstream

Denso OE Style Oxygen Sensor 234-4991

Denso 234-4991 is an OE Style heated oxygen sensor built for specific-fit replacement on select Audi applications. It is engineered for direct replacement accuracy, with a threaded mounting design, 4-wire configuration, and a 11.30-inch wiring harness length for a clean service fit.

Key Features

• OE Style replacement oxygen sensor for precise fitment
• Heated sensor design for stable exhaust monitoring
• Specific fit application with threaded mounting type
• 4-wire construction with male connector
• 11.30-inch wiring harness length
• Precision-built to match original equipment dimensions
• Uses Denso’s aluminum oxide trap layer to help protect the sensing element from silicone and lead contamination

Product Details

This Denso oxygen sensor is part of the OE Style line, which focuses on direct replacement fit and original-equipment-level construction. The sensor is manufactured and tested to OE standards, and the design emphasizes accurate installation on the intended vehicle applications. Part number 234-4991 is a specific-fit downstream oxygen sensor for select Audi models, including Audi Q7, Audi A6 Quattro, Audi A7 Quattro, Audi A8 Quattro, and Audi A7 Sportback applications listed below.

This part cross-references NTK 25244 for the same application.

Vehicle Fitment

• Fits 2020-2022 Audi Q7, downstream. O.E. Quality Direct Fit Replacement Sensor; Oxygen Sensor - OE Style.
• Fits 2019 Audi A7 Sportback, downstream. OE Style.
• Fits 2017-2019 Audi Q7, downstream. OE Style.
• Fits 2016-2018 Audi A6 Quattro, downstream. OE Style.
• Fits 2016-2018 Audi A7 Quattro, downstream. OE Style.
• Fits 2018 Audi A8 Quattro, downstream. Cylinder 4, 5, 6; OE Style.
• Fits 2015-2017 Audi A8 Quattro, downstream. Cylinder 4, 5, 6; OE Style.

What It Helps Address

• Faulty downstream oxygen sensor readings
• Check engine light concerns related to oxygen sensor performance
• Incorrect air-fuel feedback from a worn sensor
• Reduced fuel economy caused by inaccurate exhaust monitoring
• Driveability issues tied to aging emissions sensors

Installation Notes

Verify connector style, thread diameter, and harness length before installation. This sensor uses a 0.708-inch thread diameter, a male connector, and a threaded mounting type, so it should be matched to the original sensor location and configuration. Confirm downstream placement and vehicle-specific application details for the exact Audi model and engine setup.

Quality Assurance

Denso manufactures this OE Style oxygen sensor to strict original-equipment standards and tests each component for replacement accuracy and first-time fit. The sensor’s protective aluminum oxide trap layer is designed to help shield the ceramic element from contamination, supporting long-term performance in emissions control service.