Possible cat failure?

Went out on Thursday and my 1.6 petrol died

Was just getting on the motorway slip road, 2nd gear, went to over take a car and it just lost all power and the engine died.

Pulled onto the hard shoulder and left it switched off for 30 seconds and it started. It has the multifunction light on, and and points when I got to 70mph it was flashing.

Checked online and it said something about the cat?

Any ideas?