Some have an inline fuse on the back-side. When ours in the 5er aged-out, I replaced it with one from Menards. It was still functioning normally when we sold the 5er. LP detectors and CO detectors have a functional lifespan just as smoke detectors.
2000 Winnebago Ultimate Freedom USQ40JD,
ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy