I am putting in some larger fuel injectors in my 2001 Miata, with the VVT engine, in preparation for a turbo in the future.
In disconnecting the wiring I found a sensor at the back of the engine, down near the water temp sensor, mounted on the bolt that holds the sealing cap in the back of the valve cover by the exhaust cam.
It is a black, two wire connector, along with two ground leads in the same harness lead.

Can anyone tell me what this sensor is? I have looked over a wiring diagram and can not identify it with certainty. The cam angle sensor is on top of the head at the back, so it is not that. The vvt solenoid seems to be the one at the front of the engine on the vvt attachments. It seems to be vvt related, in that my 99 does not have this sensor.

Is it by chance the condensor (capacitor)?

 

Ignition noise reducer for your radio.

 

must be faulty then, the radio doesn't work
... though I expect that's because the antenna won't go up.

OK, thanks for the identification!

 

I have honestly never known what that little thing was for. I have never owned a running NB2, so I have sort of always trashed them in any engine swap.