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
Citroen C4 2.0i				Direct-fit		Universal
C4 2.0i 16v 138bhp	EW10J4 (RFN)		10/2004 onward			£ 24.95
C4 2.0i 16v 138bhp (Post Catalytic Convertor)	EW10J4 (RFN)		10/2004 onward			£ 24.95
C4 2.0i 16v 180bhp	EW10J4S		10/2004 onward			£ 24.95
C4 2.0i 16v 180bhp (Post Catalytic Convertor)	EW10J4S		10/2004 onward			£ 24.95
C4 2.0i 16v 138bhp	RFN EW10J4	Pre CAT	10/2004 onwards	£ 49.94		£ 24.95
C4 2.0i 16v 180bhp	RFN EW10J4S	Pre CAT	12/2004 onwards	£ 49.94		£ 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.