OK, so the story goes like this...
I had to get the Manifold \ cat changed recently on my 1.2 16v sporting Punto of 83k miles due to rust holes. The original Lambda sensors where removed from the old pipe and installed onto the new. Prior to this I have had no ecu errors over 8 years of happy motoring.
A few day later the warning light popped up on the dash, OBD reader says P0130 sensor 1 bank 1. Yesterday, I put a volt meter onto the 2 white heater supply cables and I only got a voltage of 8.5 volts. I was expecting to see 12volts!!! What should I be getting? Am I looking at a dodgy earth or low supply voltage that is not heating the sensor correctly!?
All things being equal, it would point at the sensor being damaged when it was removed from the old manifold as nothing much else would have been touched but the low supply voltage to the heater circuit was a bit of a surprise...

I also changed cat and new bosch sensor still get the p0130 no eml.

p0130 is the actual lambda sensor at fault, not the heater circuit. The heater circuit voltage varies with heat anyway.