I recently purchased a 4 wire o2 sensor from someone who pulled it from a low mileage 95 m3 (mileage unknown to me; although he guaranteed it functioned properly); it is an authentic oem BMW part w/ bmw insignia. Mfg by siemens, i cut the wiring only to learn that it is not compatible w/ bosch replacement due to heat respondent resistance. The sensor has imprinted upon it "Siemens 5WK9 0231", BMW emblem, NTK A 7 H, 1427884, 12V. Wiring was cut halfway, connection restored w/ crimp connectors and covered with 33+ vinyl electrical; although a solid I would recommend a using heat shrink tubing. Never installed, will try to post pics, first $30 takes it, price includes shipping within 24hrs of payment received. Thanks,
-Hunter
-Hunter