The 4-wire narrow-band oxygen sensor is a replacement sensor for 1995-1999 Ford Contour, Mercury Mystique, 1995 Ford Mystique, 2001-2012 Ford Courier, 2001 Ford Ka and 1999 Mercury Cougar in the upstream position. It signals whether the exhaust is running rich or lean so the engine computer can trim fuel delivery. A built-in heater brings the element to operating temperature quickly after a cold start.

Walker Products 350-34066 Oxygen Sensor Features:

• Fits 1995-1999 Ford Contour, Mercury Mystique; 1995 Ford Mystique; 2001-2012 Ford Courier; 2001 Ford Ka; 1999 Mercury Cougar
• Engine coverage includes 1.6L I4, 2.0L I4 applications
• Sensor location by application: B1S1 (bank and sensor number)
• 4-wire narrow-band oxygen sensor
• Built-in heater for fast warm-up
• M18x1.5 threaded mounting with a 22 mm hex, 680 mm (26.8 in.) overall length
• Male square connector at the harness end
• Platinum electrode layer with a protective coating against combustion residue