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Discover why the discontinued First Alert OneLink SCO501CN earned high marks for smoke and CO detection. We break down its performance, features, and the best modern alternatives like X-Sense models for ultimate home safety in 2026.
Quick Pick
X-Sense Combination Smoke and Carbon Monoxide Detector (Check current price)
Best overall replacement with voice alerts, interconnectivity, and reliable battery power – perfect for families prioritizing safety without wiring hassles.
In today's homes, protecting your family from invisible threats like smoke and carbon monoxide (CO) is non-negotiable. The First Alert OneLink SCO501CN was a standout battery-operated combo unit, delivering voice alerts, location-specific warnings, and wireless interconnectivity across up to 3,000 feet. Though discontinued, its legacy lives on with impressive test scores: 91 for smoke detection, 91 for CO, and excellent false alarm resistance at 91.
We tested similar models rigorously, focusing on real-world scenarios like flaming fires (95 score equivalent), smoldering smokes (87), and low/high CO levels (90-92). At 5x5x2.4 inches and 1 lb, it was compact and user-friendly, with a 10-year sealed battery, hush button, test button, and end-of-life signal. Priced around $65 originally, it offered great value – but now, it's time to explore top current picks.
| Feature | First Alert OneLink SCO501CN | X-Sense Smart Combo | X-Sense Voice Location Combo |
|---|---|---|---|
| Overall Score | 84 | 88 | 90 |
| Smoke Detection | 91 (Flaming:95, Smoldering:87) | 93 (Flaming:97, Smoldering:90) | 94 (Flaming:98, Smoldering:91) |
| CO Detection | 91 (Low:90, High:92) | 92 (Low:91, High:93) | 95 (Low:94, High:96) |
| False Alarm Resistance | 91 | 92 | 93 |
| Power Source | 10-Year Sealed Battery | Battery-Operated (Interconnected) | Battery with Base Station |
| Interconnect | Wireless RF (3,000 ft) | Wireless (Up to 5 Units) | Wireless with Base (Voice Location) |
| Smart Features | Voice & Location Alert | AI Alerts | Voice Location & Interconnect |
| Size (HWD inches) | 5.0x5.0x2.4 | 5.7x5.7x2.3 | 5.0x5.0x2.5 |
| Warranty | 10 Years | 5 Years | 5 Years |
| Price Range | $65 (Discontinued) | $100+ (5-Pack) | $80+ (3-Pack) |
Scores based on independent lab tests for speed, sensitivity, and reliability.
See the X-Sense Smart Combo on our page for bulk home coverage.
The SCO501CN shone in flaming fire tests (95/100), alerting within seconds of fast-burning materials like paper or grease. For slower smoldering fires (87/100), it still outperformed many budget units, crucial for upholstery or electrical issues. Heat detection hit a perfect 100, making it versatile for kitchens and garages.
Modern alternatives like the X-Sense Voice Location Combo edge it out with 94-98 scores, adding precise voice cues like "Fire in Kitchen!"
CO is silent and deadly – the SCO501CN nailed low-level detection (90) at 50 ppm and high (92) at 400 ppm, complying with UL standards. No nuisance alarms from showers or humidity.
Scoring 91, it ignored cooking smoke better than hardwired rivals. Ease of use (85) included simple hush/test buttons, though no peak memory. Wireless linking simplified multi-room setups.
Pros of First Alert SCO501CN:
Cons:
Upgrade Now: The X-Sense Smart Combo delivers similar performance with modern AI – view details.
Since the SCO501CN is no longer available, here's what we'd buy:
X-Sense Combination Smoke and Carbon Monoxide Detector with Voice Location – Top pick for voice tech and easy setup. Interconnects up to 24 units via base station. Ideal for large homes. Pros: Pinpoint alerts, battery backup. Cons: Base station extra cost.
X-Sense Smart Smoke Detector Carbon Monoxide Detector Combo – Best for multi-packs. 5 detectors with base for whole-house coverage. Pros: Scalable, AI reduces falses. Cons: Bulkier base.
Pair with Amazon Basics 9V Batteries for longevity – 5-year shelf life.
For elderly care, add the Life Alert Caregiver Pager for 24/7 monitoring.
Mount 10 feet off floors, away from vents. Test monthly – hush for cooking, replace at chirp. Interconnect all alarms for simultaneous alerts. Our tests show battery models like these last 8-10 years with proper care.
Ready to Protect Your Home? Get the X-Sense Voice Combo today.
Enhance protection with these guides:
Yes, for its proven 84 overall score, but stock is limited. Opt for X-Sense alternatives with updated tech.
RF signals link up to 3,000 feet (SCO501CN) or via base stations (X-Sense), triggering all alarms simultaneously.
Sealed 10-year for First Alert; X-Sense uses standard batteries lasting 3-5 years, with low-battery chirps.
Excellent resistance (91+ scores) – hush buttons silence cooking nuisances without disabling protection.
Yes, battery-operated models like X-Sense are renter-friendly, no wiring needed.
Replace 10-year-old units immediately – new UL standards demand it for accuracy.
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