Walker 350-31003 Oxygen Sensor - Upstream

Walker 350-31003 Oxygen Sensor Overview

Walker Products 350-31003 is a specific-fit oxygen sensor engineered as an OE-style replacement for select older Ford, Kia, Mazda, and Mercury applications. It is built for upstream Bank 1 Sensor 1 locations where accurate exhaust feedback is needed for engine management and emissions control.

With a threaded mounting design, 18.0 mm thread diameter, 20-gauge single-wire construction, and a radiused polygon female connector, this sensor is matched to the listed vehicle applications and ECU feedback requirements.

Key Features

• Part number: 350-31003
• Specific-fit oxygen sensor for upstream applications
• Non-heated sensor design
• Single-wire configuration with 16.46 wiring harness length
• Threaded mounting type with 18.0 mm thread diameter
• Radiused polygon female connector
• Overall length: 20.0
• Walker Products Aftermarket product line for engine management and oxygen/air-fuel sensors

Detailed Description

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors built for direct replacement use across many vehicle platforms. The 350-31003 is manufactured for the specified application and fitment position so the ECU receives the expected diagnostic feedback from the upstream sensor location. This part number is listed for 1990-1995 Mazda 323, 1990-1994 Mazda Protege, 1992-1993 Mazda MX-3, 1990-1993 Ford Festiva, 1991-1994 Ford Escort, 1991-1994 Mercury Tracer, and 1994-1995 Kia Sephia upstream oxygen sensor applications.

This part cross-references no listed interchange numbers in the provided data. For buyers searching by fitment, this is a Walker 350-31003 oxygen sensor for 1991-1994 Ford Escort upstream, 1990-1994 Mazda 323 upstream, and 1994-1995 Kia Sephia upstream applications.

What It Helps Address

• Check engine light related to upstream oxygen sensor faults
• Poor engine performance caused by incorrect exhaust feedback
• Increased fuel consumption from inaccurate air-fuel readings
• Higher exhaust emissions from a failing sensor
• Diagnostic trouble codes stored in the ECU for sensor-related issues

Installation Notes and Tips

Confirm the vehicle year, make, model, and upstream Bank 1 Sensor 1 position before ordering. Inspect the sensor, wiring harness, and connector for physical damage during diagnosis, since damaged wiring or connectors can shorten service life and affect readings. Use the listed threaded mounting and connector style to verify physical match before installation.

Quality Assurance

Walker Products states that its engine management sensors are developed as OE replacement parts and manufactured under Automotive ISO9001/TS 16949 certification standards. The brand has supplied engine management and fuel system components since 1946.