The 4-wire narrow-band oxygen sensor is a replacement sensor for 2007-2011 Ford Focus, 2009-2015 Ford EcoSport and 2010-2013 Ford Transit Connect with the 2.0L I4 engine 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 350-34028 Oxygen Sensor Features:

• Fits 2007-2011 Ford Focus; 2009-2015 Ford EcoSport; 2010-2013 Ford Transit Connect with the 2.0L I4 engine
• 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, 475 mm (18.7 in.) overall length
• Male/female square connector at the harness end with 4 pin terminals
• Platinum electrode layer with a protective coating against combustion residue