How do you replace oxygen sensor on citroen xsara?

To replace the oxygen sensor on a Citroën Xsara, first, locate the sensor, which is typically situated in the exhaust system, either before or after the catalytic converter. Disconnect the battery to ensure safety, then unplug the electrical connector from the sensor. Use an oxygen sensor socket or wrench to unscrew the old sensor, and install the new one by threading it in and tightening it securely. Finally, reconnect the electrical connector and the battery, and check for any error codes using an OBD-II scanner if necessary.