Post-Cat Oxygen Sensor, Bosch - E46 325/330 (late), E60, X3 - 11787514926

E46 325i/330i bank 1 post-cat O2 sensor (cylinder 1-3, after the catalytic converter).

Note for E46 Models: for 3/2003 production and later only. This includes all 2004, 2005 and 2006 M54 models. If you have a 2003 model, you will need to check your production date. Not for cars built before 3/2003. 

This the oxygen sensor (O2 or Lambda probe) located after the catalytic converter. It reads and checks the status of the exhaust after going through the catalytic converter. The engine computer uses this data to verify the cats are working properly. A failed O2 sensor can set several different types of fault codes so it's a good place to start if you have O2 sensor or heater circuit faults. Most cat manufacturers will insist that you have new post-cat O2 sensors when you install new cats. This is a new OEM O2 sensor from Bosch, the inventors of the system and the original supplier to BMW. Note: for 3/2003-2006 models only.