Just an FYI, my CO detector was making a real high pitch squeal (like when your ears ring) all the time. After reading someones post about it, I called the manufacturer of the detector and they advised that they had a batch that had a loose speaker coil in them that caused the squeal, and they had me send the old one to them and they replaced it for no charge. My TT production date was somewhere around 6-2010. I was very pleased with the CO detector manufacturer on that one.
Also, if you check your regular house CO detectors, they all have the 5 year replacement dates also. It's the detector material, it gets used up after the 5 years.
2011 Jay Filght G2 32BHDS
2008 Silverado 2500HD 4WD 6.0L
Reese DC, Prodigy controller