When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I ahve used 8-10 of them form three different sources and about half are right out of the box. Not sure what the mystery is. If it is wrong it will pop and fart but probably run and you will get the sensor fault. Then just flip the wires.