Noisy front bearing
Sometimes the advice gleaned from a friend down the pub is not always the best information on which to base a diagnosis.
The owner of this 2008 Nissan Qashqai insisted the 02 sensor was faulty due to a random comment made by a mate. Driving us around the block to show us the fault, she pointed out the humming noise coming from the offside front wheel bearing.
This made the repair much easier: we simply needed to replace the bearing, not the sensor, despite what her friend had said. Fitting a new bearing on the Qashqai is particularly easy as the bearing and hub assembly are in a single unit that is simply bolted in place. The one thing to watch is to ensure that the ABS sensor is detached before trying to remove the hub from the carrier.
Remember to disconnect the ABS sensor before removing the hub.