The answer to 'why is my carbon monoxide detector outlet not working' is that the outlet may not be providing power to the detector. Common causes include a tripped circuit breaker, a faulty outlet, or a wiring issue. Symptoms may include the detector not powering on or displaying error lights.
To troubleshoot, first check the circuit breaker to ensure it has not tripped. If the breaker is fine, use a voltage tester to check for power at the outlet. If there is no power, the outlet may need to be replaced by a professional electrician. If the outlet has power, the issue could be with the carbon monoxide detector itself, which would need to be repaired or replaced.