This is assuming you don't have access to a scantool that can communicate with a Honda ECM and without bidirectional controls.
Key On Engine Running (this may work Key On Engine off) disconnect the Air Fuel Ratio sensor connector. On the harness side connector Check for power on pin 4 (white). Check for ground on pin 3 (white/black).
If you don't have power on pin 4. Locate the Primary Heater Control Relay in the passenger under dash fuse box.
Pull or backprobe the relay/connector.
Pin 30 (red/blue) - pulls power from fuse 6 of the passenger under dash fuse box.
Pin 87 (white) - is relay output to the ECM and AFR sensor.
Pin 86 (green/red) - is the relay coil control wire from the ECM.
Pin 87a - is unused and may be blank.
Pin 85 (black/yellow) - is the relay coil power, fuse 6 in the under hood fuse box.
If pins 30 or 85 don't have power check their respective fuses. If the fuses are OK, check continuity between the fuse terminals and the relay pins. Repair as necessary.
If you don't have ground on pin 86 backprobe pin 16 on the B connector at the ECM. If ground exists, check continuity on the circuit. Repair as necessary.
If you don't have power on pin 87 with the relay plugged in. Replace the relay.
If you don't have power on pin 4 of the AFR sensor connector, but have power on pin 87 of the relay. Check continuity between relay pin 87 and AFR sensor connector pin 4. Repair as necessary.
If pin 87 on the relay has power and pin 4 of the AFR sensor connector has power check for power at the ECM connector C pin 13 (white). If power exists and you have ground on pin 3 of the AFR sensor connector. Replace the AFR sensor first. If the code comes back replace the ECM.