Genuine BMW 428i Oxygen Sensor

BMW 428i Oxygen Sensor Parts Questions & Experts Answers

• Oxygen Sensor
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  Q: How to remove and install the pre- and post-catalyst oxygen sensors on N20, N26, and N55 engines on BMW 428i?

  A:

  Oxygen sensors are positioned at both the front and back of the Catalytic Converter. Make sure you use a BMW scan tool or equivalent to read and clear the ECM fault codes before removing these sensors. Oxygen sensors are very sensitive to shock, so handle with care. Also, it's a good idea to mark the connectors so you don't mix them up. First, remove the engine covers and unplug the oxygen sensor harness connectors. Take out the fastener and connector bracket if required. The wiring on the pre-catalyst is black, grey on the post-catalyst. For the N20 and N26 engines, remove the pre-catalyst oxygen sensor from the catalytic converter using an oxygen sensor socket. During installation, apply some anti-seize on the sensor threads. Ensure the electrical harness connectors are routed and connected properly. Before removal of N55 engine, unplug pre-catalyst oxygen wire. When employing tool 11 4 260, lower the tightening torque by 3 Nm, or to 47 Nm (35 ft-lb). For post-catalytic converter oxygen sensors, repeat the steps of removing the engine covers and disconnecting the harness connectors and removing the exhaust system and catalytic converter. For the N55 engine, unplug the grey post-catalytic O2 wire. After securing the converter in a vice without damaging it, use the oxygen sensor socket to remove the post-catalyst oxygen sensor. Apply some anti-seize compound on the threads during installation and ensure the electrical harness connectors are routed and connected properly. Do not get lubricant on the sensor tip.