P0037 Subaru - Is this the upstream before cat o2 sensor?

Question

We changed the upstream before cat O2 sensor and it is still throwing the P0037 code. We checked the fuse for the O2 sensor and it is fine. With a new O2 sensor, it cannot be the wires, so what else could cause this issue? Thanks.

Answer 1

P0037 Rear oxygen sensor heater circuit malfunction

This code is for the downstream 02 sensor. This is after that catalytic