Help needed PO420

Evening all,
Was driving to pick up the kids when the engine management light came on.

I've plugged in my mates obd tool and it's coming up saying Catalyst System Efficiency Below Threshold (Bank 1)

Is this the lambda sensor or should I be checking else where.

Any input would be much appreciated.

hey have a look here at the list of checks and fix's 🙂
http://www.obd-codes.com/p0420

Thanks buddy.
I'll try have a check over the car at some point over the weekend.

Car drives fine with no loss of power ect 😉