First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup

Short answer: The CO606 is the best of both worlds in First Alert's lineup — it plugs into a standard 120V outlet for permanent installation, but the included 9V battery backup keeps it running during power outages. This matters because power outages are exactly when CO risk spikes: people run generators indoors, use propane heaters, or light candles near gas appliances. If you're choosing between the CO600 and CO606 for a permanent installation, the CO606 is the right call.

Why Battery Backup Matters for CO Detection

First Alert CO Alarm Comparison

Installation Guide

• Install the 9V backup battery before plugging in
• Plug into a standard 120V outlet — unit activates immediately
• Press the test button to verify alarm function
• Mount height: 5 feet from floor on walls near outlets, or on outlet covers at outlet height — CO disperses throughout the room, not just at ceiling level
• Required locations: outside each sleeping area and on each level of the home (NFPA 720)
• Replace backup battery annually — the unit will chirp to signal low battery

Frequently Asked Questions

How do I know the battery backup is working?

Press the test button — it tests both AC power detection and battery backup. If the backup battery is low or missing, the CO606 will emit a distinct low-battery chirp pattern (different from the alarm and end-of-life signals).

Can I use a rechargeable 9V battery in the CO606?

First Alert recommends standard alkaline 9V batteries only. Rechargeable batteries have a lower voltage output that may not provide sufficient power for reliable backup operation.

What's the end-of-life signal?

After approximately 7 years, the electrochemical sensor degrades to a point where accurate CO detection is no longer reliable. The CO606 emits a specific chirp pattern (typically 5 chirps every 30 seconds) that differs from the low-battery or CO alarm patterns, indicating the unit should be replaced. Do not silence and continue using a unit that has issued an end-of-life warning.

Is the CO606 interconnectable with other alarms?

The CO606 is not designed for hardwired interconnect. For interconnected systems (where all alarms sound when one detects CO), look for First Alert models with the OneLink wireless interconnect feature or hardwired interconnect capability.

How does it meet UL 2034?

UL 2034 is the Underwriters Laboratories standard for single and multiple station CO alarms. It specifies alarm thresholds that prevent nuisance alarms at low CO levels while ensuring alarm at concentrations that pose health risk. The CO606 is UL 2034 listed, satisfying the requirements referenced by NFPA 720 and most state CO alarm codes.