Error code P0135

Hi guys,
So after putting up with the engine light being on for close on a year, I've decided to do something about it!
Using EOBD app on my Ipad & an EBay wifi OBD2 reader I've got a message that reads...

O2 sensor heater circuit malfunction ( bank 2 sensor 1).

So questions, I've been advised before that this is the manifold sensor, does everyone agree?
Is there a test for the heater circuit, as it's a heating element in the sensor I'm guessing that someone knows what the resistance should be, I'd like to check that before getting into checking back through the wiring?

Any help & advise thankfully received....

Thanks guys,

Ps, the app seems an absolute bargain, basic functions for free, upgrade is £10.99 & gives fault code reset facilities, real time recording etc, that and the OBD2 for £13 delivered is great value...

How many sensors do you have

Unless you have a V engine fitted then you don't have a Bank 2. P0135 is Bank 1, sensor 1 which is indeed the manifold sensor.

2, one in the manifold & one at the Cat

usually the one in the manifold changed 2 in last year at work and had to do my own 3 weeks ago

Thanks to everybody for their help, new 02 sensor fitted & DTC cleared, happy days.....now just the heater matrix to sort........