Slightly more frightening appears to be not only is it useless, its damaging! After yesterdays test drive both my Wideband AFR sensors in the manifold are toast, or rather probably poisoned by the decaying ceramic coat inside the pipes. If one sensor had gone bad I'd have dismissed it, but two at the same time? And I've tested its not the controller because plugging a spare in and doing a calibration run it works perfectly.   I know leaded petrol kills the sensors, as well as silicon fumes, wo