The answer to 'how much to replace carbon monoxide detector in Illinois' is that the cost to replace a carbon monoxide (CO) detector can vary depending on several factors. Generally, you can expect to pay between $20 to $100 for a new CO detector, plus any labor costs if you hire a professional electrician to install it.
The price range depends on the type of detector, the features it offers, and whether it's a basic model or a more advanced one with additional sensors and connectivity. Hardwired detectors with battery backups tend to be on the higher end of the price range, while basic plug-in or battery-operated models are usually less expensive. Additionally, the cost may be influenced by your location within Illinois, as prices can vary by region.