The story from the top....
Lots of issues (codes) being generated by the OBD. Cruise had stopped working, dash reporting brake switch had failed. He took it into garage and they replaced the front O2 sensor and fitted a new brake switch. Later is two pole, one for brake lights other for ECU(?).
Had thought with all of the codes randomly being generated, that the ECU was failing.
It came back with pretty much the same faults showing, so we had a another look at it, thinking the brake switch fault and cruise failure might be related to the cruise ECU having no supply. The manual didn't suggest which fuse powered the cruise, so went through every fuse in the car, looking for any which were blown. Found one which had blown and replaced it.
That fixed most of the issues, cruise brake switch and all of the fault codes, except one. Performance now much better. Not happy about the garage not noticing the blown fuse, replacing a perfectly good brake switch and maybe the O2 sensor. It now complains Oxygen sensor 1, bank
1 heater and an occasional fuel trim code. Checked resistance of the heater and it showed 17 Ohm, which is within spec. With engine warm and O2 unplugged, checked for voltage feeding heater, measured 0.4v. What I don't know, is should the heater circuit be switched off by the ECU, once the engine is warmed up.Any other suggestions welcome please.