my fd is stock ware is this sensor do i need it whare can i buy it i tried to do research but came up empty handed.

 

The stock knock sensor is located on the front rotor housing. There is a single wire which should be insulated by soft black goo. It basically looks like an oversized lug nut. For one, make sure it's plugged in before you begin to search for a replacement. The connection should be a black single pin/wire plug near the oil filler neck.

If you were to replace it with an OEM unit from Mazda, it will cost quite a bit. You can buy a good condition one from Fritz Flynn or someone else and save some money.

 

Sensor is located on the front rotor housing above the spark plugs (has a single wire comming off it) more than often its the wire that is broken or a bad connection on these sensors.