Answer
May 22, 2025 - 11:00 AM
Ah, replacing the O2 sensors on a Micra K12 ain't too bad. You’ve got two of ’em:
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Upstream (before the cat) on the exhaust manifold,
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Downstream (after the cat) under the car.
First, let the car cool off (trust me, those sensors get crazy hot). Then disconnect the battery just to play it safe.
The sensors have electrical connectors, so unplug them gently and don't pull the wires. Then use an O2 sensor socket or a 22mm wrench to back them out. A little WD-40 or PB Blaster helps if they're crusty.
Thread the new ones in (a dab of anti-seize if they don’t already have it), snug them up, then plug the connectors back in.
Once you fire it back up, you might need to clear the check engine light with a scanner, especially if it was throwing a code.
If you want the full diagrams, wiring, or torque specs (which you need for doing this job properly), I recommend you grab the manual. It’s got everything and makes life easier down the road.
Good luck!
