It doesn't "seem to be" faulty, but when you use the manufacturer's software to test it, it fails. I bought one, returned it on the advice of the manufacturer, received a second one, it also had the same problem, so returned it also. Using CyberPower's software, "PowerPanel Personal", the "Self-Test" appears to pass, but when you look at the "Event Log", it shows two results for the "Self-Test". The first is a FAIL, the second is a pass. Only the second result is communicated to the "Self-Test" function. When I communicated with CyperPower about this, they said it was a problem, and to return it. Having tested two of these, and they both had the same problem, I strongly recommend that no one take a chance on this model of UPS.