This 4-wire narrow-band oxygen sensor fits 1989-1992 BMW 525i with the 2.5L I6 engine 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 350-34038 Oxygen Sensor Features:

• Fits 1989-1992 BMW 525i with the 2.5L I6 engine
• 4-wire narrow-band oxygen sensor
• Built-in heater for fast warm-up
• M18x1.5 threaded mounting with a 22 mm hex, 750 mm (29.5 in.) overall length
• Female circle connector at the harness end
• Platinum electrode layer with a protective coating against combustion residue