Pre-Cat Oxygen Sensor, Bosch - E46 325/330 (late), E60, X3 (11787523434)
E46 325/330: 3/2003-2006. OEM Bosch bank 1 pre-cat O2 sensor. 24 month warranty.
E46 325/330 built 3/2003 through 2006, E60 525i/530i 04-05, E83 X3 2.5i/3.0i bank 1 pre-cat O2 sensor (cylinders 1-3, before the catalytic converter).
The pre-cat O2 sensors, also known as Lambda probes, on the E46, E60, and X3 are some of the most important sensors on the M54 engine. The pre-cat sensor is 1010mm in length, and tells the engine computer how well the engine is working (note: not how clean it is, that's the post-cat sensor). The pre-cat sensors give the ECU feedback on the engine tuning - if it's running lean or rich - and the ECU makes adjustments based on their data. Each bank of cylinders has its own sensor before and after the catalytic converters (this part number is the same sensor for both banks). The ECU adjusts fuel injection based on the data so the sensors also affect fuel economy in addition to performance. An integrated heater circuit helps prolong the life of the sensor but can also fail and give a check engine light.
Fitment not on E46: Not for cars built before 3/2003. This O2 sensor is only for the later cars, with a production date of March 2003 or later, which includes all 2004, 2005 and 2006 model.
Signs of an O2 sensor failure include worse fuel economy, lack of torque, and fault codes for the sensor(s). It is a good idea to replace the O2 sensors at regular intervals rather than waiting for a failure. Since their performance degrades over time you may not even notice the loss in performance or economy. Since the complete O2 sensor is part of the emissions system, a bad sensor may not set multiple OBD Readiness flags.
This is a genuine Bosch E46 E60 X3 O2 sensor. Bosch is the original supplier to BMW for oxygen sensors, as well as the inventors of the system.
E46 (99-05) > 325Ci
E46 (99-05) > 325i
E46 (99-05) > 330Ci
E46 (99-05) > 330i
E60 / E61 (04-10) > 525i M54 (2004-2005)
E60 / E61 (04-10) > 530i M54 (2004-2005)
E83 X3 (04-10) > X3 3.0i M54 (2003-2006)