Current news reports (in the UK) state that some petrol stations might
be supplying contaminated lead-free petrol, which damages the O2
sensor and possibly the cat converter.

So what happens if the lead from the sensor is merely disconnected at
the ECU end of the cable?

After all this is just one of many inputs to the engine management
system. ISTR that engines ran quite well before the O2 sensor was
invented

David

The system will run at "full rich", wasting fuel, possibly dilute the oil
and fouling plugs, run terrible, and it won't protect the O2 sensor from the
bad fuel.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty