The 4-wire narrow-band oxygen sensor is a replacement sensor for 1994-1995 BMW 530i, 1994 BMW 540i, 1995 BMW 740i, 740iL and 840Ci 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 350-34139 Oxygen Sensor Features:

• Fits 1994-1995 BMW 530i; 1994 BMW 540i; 1995 BMW 740i, 740iL, 840Ci
• Engine coverage includes 3.0L V8, 4.0L V8 applications
• 4-wire narrow-band oxygen sensor
• Built-in heater for fast warm-up
• M18x1.5 threaded mounting with a 22 mm hex, 360 mm (14.2 in.) overall length
• Male circle connector at the harness end
• Platinum electrode layer with a protective coating against combustion residue