I have a Toyota Aygo, purchased new in September 2015. Just before it was five years old it needed a replacement oxygen sensor, at about 17,000 miles. To their credit, this was done by Toyota under the warranty. Just 14 months later I had dashboard warning lights appear and was told the car needed a further oxygen sensor. This was not under warranty (the first replacement sensor was just more than 12 months old) and I had done only a further 3,000 miles. This time I had to pay for the sensor as I was told all the warning lights it had 'triggered' represented an MOT failure. General info on the internet seems to indicate these sensors should be 'good' for 60,000 miles or so. I have had two fitted so far, on about 20,000 mileage and, in fact, two within 14 months and about 3,000 miles travelled. Is there a known 'issue' with these sensors, either in design or manufacturing quality?