Walker 350-34066 Oxygen Sensor - Upstream

Walker 350-34066 Upstream Oxygen Sensor

Walker Products 350-34066 is a heated, specific-fit upstream oxygen sensor engineered as an OE-style replacement for select Ford and Mercury applications. It is built to deliver the diagnostic feedback the ECU expects, helping maintain proper air-fuel control on vehicles such as the Ford Courier, Ford Contour, Mercury Cougar, and Mercury Mystique.

Walker Products Aftermarket focuses on engine management and oxygen/air-fuel sensors for application-specific fitment. The 350-34066 follows that approach with a threaded mounting design, 18.0 mm thread diameter, 4-wire construction, and a radiused polygon male connector for direct replacement use.

Key Features

• Heated oxygen sensor for upstream placement
• Specific-fit design for confirmed vehicle applications
• 4-wire sensor layout with 20-gauge wiring
• 24.33 in. wiring harness length and 27.87 in. overall length
• Threaded mounting type with 18.0 mm thread diameter
• Radiused polygon male connector for vehicle-specific connection

Detailed Description

Walker 350-34066 is designed for upstream oxygen sensor service where accurate exhaust feedback is needed for ECU fuel-trim control. It is listed for 2008-2012 Ford Courier, 2001-2007 Ford Courier, 1995-1999 Ford Contour, 1999 Mercury Cougar, and 1995-1999 Mercury Mystique in upstream positions. For shoppers searching for a Ford Courier upstream oxygen sensor or a Mercury Mystique Bank 1 Sensor 1 replacement, this part number provides a direct-fit option built around the original application requirements.

As an OE replacement from Walker Products Aftermarket, this sensor is intended to match the fitment position and diagnostic function required by the vehicle’s engine control system. The heated design helps the sensor reach operating temperature quickly, supporting stable feedback once installed in the correct upstream location.

What It Helps Address

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

Installation Notes and Tips

Confirm the vehicle’s upstream sensor location before ordering, since this part is specific to the application and position. Inspect the sensor wiring harness and connector for damage during replacement, and verify the threaded mounting point is clean before installation. If the original sensor failed due to wiring or connector damage, correct that issue before installing the new unit.

For fitment-focused searches, this part number is commonly referenced as Walker 350-34066 for Ford Courier upstream oxygen sensor service and Walker 350-34066 for Ford Contour and Mercury applications.

Quality Assurance

Walker Products has manufactured engine management and oxygen/air-fuel sensors since 1946 and operates as an Automotive ISO9001/TS 16949 certified company. The 350-34066 is built to support the diagnostic feedback expected by the ECU in the listed applications.