Walker 350-34493 Oxygen Sensor - Downstream

Walker 350-34493 Oxygen Sensor Overview

Walker Products 350-34493 is a heated downstream oxygen sensor built as a specific-fit OE-style replacement for select Nissan Quest and Mercury Villager applications. It is engineered to provide the ECU with the exhaust feedback needed for proper fuel control and emissions monitoring.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for application-specific fitment, making this part a direct replacement for the listed downstream positions on 1998-2000 vehicles.

Key Features

• Heated oxygen sensor for downstream exhaust monitoring
• Specific fit design for the listed vehicle applications
• 4-wire configuration with female connector
• Threaded mounting type with 18.0 mm thread diameter
• Wiring harness length: 30.24 in.; overall length: 33.78 in.
• Radiused polygon connector shape for application-specific connection

Detailed Product Description

The Walker 350-34493 oxygen sensor is designed for downstream placement on 1998 Nissan Quest, 1999-2000 Nissan Quest, and 1999 Mercury Villager models listed without California emissions certification. As a heated sensor, it helps the engine control system monitor exhaust conditions after the catalytic converter and maintain accurate diagnostic feedback to the ECU. This part number, 350-34493, is built for specific fitment rather than universal use, which helps simplify replacement on the correct downstream location.

Walker Products Aftermarket develops engine management sensors as OE replacement parts for many vehicles worldwide. For Nissan Quest and Mercury Villager owners searching for a downstream oxygen sensor replacement, 350-34493 provides the correct threaded, 4-wire configuration for the listed applications.

What This Oxygen Sensor Helps Address

• Check engine light related to downstream oxygen sensor faults
• Poor fuel economy caused by inaccurate exhaust feedback
• Elevated exhaust emissions from a failing sensor
• Rough engine operation tied to sensor signal issues
• Diagnostic trouble codes stored in the ECU for the affected sensor circuit

Installation Notes and Tips

Confirm the vehicle is one of the listed non-California emissions applications before ordering. This sensor is for downstream placement only, so match the original sensor location, connector style, wire count, and thread size before installation. Inspect the sensor wiring harness and connector for heat damage, abrasion, or corrosion, since physical damage can shorten service life and affect signal quality.

For fitment-based searches, this part fits 1998 Nissan Quest, downstream; fits 1999-2000 Nissan Quest, downstream; and fits 1999 Mercury Villager, downstream. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

Quality Assurance

Walker Products has manufactured engine management and oxygen sensor components since 1946 and operates as an Automotive ISO9001/TS 16949 certified company. The 350-34493 part number is produced for the specified application and position to support proper ECU feedback on the listed vehicles.