This 4-wire narrow-band oxygen sensor fits 1995-1999 Ford Contour, Mystique, Mercury Mystique and 1999 Mercury Cougar with the 2.5L V6 engine in the upstream position and 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 350-34588 Oxygen Sensor Features:

• Fits 1995-1999 Ford Contour, Mystique, Mercury Mystique; 1999 Mercury Cougar with the 2.5L V6 engine
• Sensor locations by application: B1S1, B2S1 (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, 375 mm (14.8 in.) overall length
• Male square connector at the harness end
• Platinum electrode layer with a protective coating against combustion residue