Hello Ian, Had similar problem with mine, seemed to be the tiny terminals in the connecter on the O2 sensor. Are you sure the new sensor is good? Obviously the old one is U/S as the new one worked as soon as you fitted it. Possibly a faulty new sensor? Other than that, I can't help as far as knowing a technician in your part of the world, but Glenn Friedman of Independant Tuning Supplies does repair and calibration on these, and he is very good. He is based in Kent, I don't know his phone number but he has a web site under his trade name, hope this helps, regards, Gwyn