ok fitted new probe, still getting p0135 error message after about 3k miles covered, I reset it, the car starts 3 or 4 times as normal then error message appears, cleaned connector plug/socket, can't be fuse as it starts as above  anybody any suggestions, intermittent fault with heater etc?

i'm stuffed if I can come up with a reason apart from a faulty new probe!

We had a 308 with a similar issue which was eventually resolved by swapping pre and post cat sensors.

I found it hard to believe but it never returned.    It seems in the world of ohms stuff happens.