The oxygen sensor installs in the downstream position on 2015-2018 BMW M3, 2015-2020 BMW M4 and 2019-2021 BMW M2 with the 3.0L I6 engine. It signals whether the exhaust is running rich or lean so the engine computer can trim fuel delivery. It uses a male/female rectangle connector with 4 terminals.

Walker Products 250-241179 Oxygen Sensor Features:

• Fits 2015-2018 BMW M3; 2015-2020 BMW M4; 2019-2021 BMW M2 with the 3.0L I6 engine
• Sensor location by application: B1S2 (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, 675 mm (26.6 in.) overall length
• Male/female rectangle connector at the harness end with 4 pin terminals
• Platinum electrode layer with a protective coating against combustion residue