Direct-fit & Universal Oxygen Sensor Application List

Also known as O2 sensors, HEGO sensors, Lambda sensors

Model	Engine Code	Chassis	Years	Price  inc VAT and P&P = in stock
BMW 525i 2.5i				Direct-fit		Universal
525i 2.5i 12v 170bhp Saloon	M20	E34	9/1998 to 9/1990			£ 24.95
525i 2.5i 12v 192bhp Saloon	M50	E34	9/1990 to 6/1992			£ 24.95
525i 2.5i 24v 192bhp Saloon	M52	E34	9/1994 to 9/1996			£ 24.95
525i 2.5i 24v 192bhp Touring	M52	E34	9/1994 to 9/1996			£ 24.95
525i 2.5i 24v 192bhp	M54	E39	9/2000 to 2/2004			£ 24.95
525i 2.5i 24v 192bhp Touring	M54	E60/E61	5/2004 to 1/2005			£ 24.95
525i 2.5i 24v 192bhp Touring (Post Catalytic Convertor)	M54	E60/E61	5/2004 to 1/2005			£ 24.95
525i 2.5i 24v 192bhp (Post Catalytic Convertor)	M54	E39	9/2000 to 2/2004			£ 24.95

Pre-cat / Post-cat? What does that mean?

• There will be at least one sensor at the front of the vehicle, mounted into the exhaust pipe or manifold somewhere before the catalytic convertor.
  This is known as the front, pre-cat or upstream sensor.
  V-type engines (V6, V8 etc) will often have one pre-cat sensor for each bank of cylinders.
  
  
• There will then be another sensor positioned after the catalyst, known as the rear, post-cat or downstream sensor.
  Under normal circumstances, the rear sensor does not have any direct impact on the fuel mixture (and therefore the running and emissions of the engine) - it is there to offer a comparison value after the catalyst, allowing the car to monitor the performance of the cat.