Important information you should know about O2 sensors.
Due to thermal aging and O2 sensor design and construction characteristics, their efficiency will deteriorate over time.
O2 sensors should be check every 20,000 miles (Febi quote)
O2 sensors should be replaced between 30,000 & 100,00 miles (Bosch quote)
O2 sensors should be replaced if the CAT is replaced (Febi & Bosch quote)
So in other words, you should see your O2 sensors as serviceable items around the 60-80k service period, as well as if you switch to a Sports Cat or Decat. This will ensure your car is efficient and well placed for emissions testing during MOT’s.