The 4-wire narrow-band oxygen sensor is a replacement sensor for select 2014-2021 BMW applications in the downstream 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 250-241161 Oxygen Sensor Features:

• Fits 2014-2015 BMW 335i, 335i xDrive, ActiveHybrid 3; 2014-2016 BMW 435i, 435i xDrive, ActiveHybrid 5, M235i, i8; 2014-2018 BMW X5; 2014-2021 BMW i3
• Fits 2015-2016 BMW 435i Gran Coupe, 435i xDrive Gran Coupe, M235i xDrive; 2015-2018 BMW M3; 2015-2020 BMW M4; 2016-2021 BMW M2; 2016-2018 BMW X4
• Also fits select BMW applications
• Sensor locations by application: B1S2, B2S2 (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, 550 mm (21.7 in.) overall length
• Male/female rectangle connector at the harness end with 4 terminal terminals
• Platinum electrode layer with a protective coating against combustion residue