Thanks dave will register and take a look.

Fault was present on Toyota original cat and Would take a month then same code.
Customer had a TA cat and oxy,s fitted same re occurrence 1 month later,

So cat quality has a question mark over it yes.
I have disconnected battery and powered down to allow eobd reset.

Possible intermittent fueling fault?
next step...air mass and lambda signal tests with scope to establish correct fueling operation.
iatn look up also.
will post when done.

thanks Simon