This 4-wire narrow-band oxygen sensor fits 1987-1991 BMW 325i, 1988-1991 BMW 325iX, 325is and 1994-1995 BMW 850CSi 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 350-34584 Oxygen Sensor Features:

• Fits 1987-1991 BMW 325i; 1988-1991 BMW 325iX, 325is; 1994-1995 BMW 850CSi
• Engine coverage includes 2.5L I6, 5.6L V12 applications
• 4-wire narrow-band oxygen sensor
• Built-in heater for fast warm-up
• M18x1.5 threaded mounting with a 22 mm hex, 630 mm (24.8 in.) overall length
• Female circle connector at the harness end
• Platinum electrode layer with a protective coating against combustion residue