Ensure the oxygen sensor’s heater circuit element is within the OEM’s specifications.
If using the heater circuit simulator included with the iO2SS, ensure it is connected to the correct wires.
Inspect the wiring harness for open circuits.
Ensure the oxygen sensor heater circuit’s fuse isn’t blown.
If this problem persists, your car may require a lower resistance heater circuit simulator. In this case, contact support@symtechlabs.com for further support.