Code P0038?

Hello, the p0038 is the heater circuit for the rear oxygen circuit. That's why it's not activated.
Verify there are 12-volts and ground across pins 1 and 2, looks like the brown/violet wire and the black wire is Ground with the key on. Most of these heater circuits are now pulse width modulated, so if you use a test light to check the circuit and back probe the 0xygen sensor connector you will probably see a dimly flashing light with the engine running. I will post the wiring diagrams and OEM diagrams to back those up. But that's why the code is setting. There might be a broken wire somewhere, depending on the route the wiring takes from the rear sensor. The aftermarket diagram is first,
there are no OEM diagrams for the heater circuits for some reason. Thats been happening a lot lately, but there should be 2 wires with 12volts across them for the heater. Sometimes at the sensor they are the same color wires. But the 2nd diagram shows the Oxygen sensor connector, if you are missing the 12volts, which most likely you are, you'll have to trace the wires back to find the open circuit. These wires sometimes run up into the body of the vehicle and are supposed to be in a rubber grommet, but the wire can break these points if it is rubbing against a contact point of the vehicle.
It looks like the ECM is under the air filter housing, but some of these diagrams can be incorrect. But I think you will find either a broken power feed or Ground to the rear Oxygen sensor. The Ground itself is supposed to be shared with the front Oxygen sensor heater, so hopefully it is just a broken wire.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter