Quote Originally Posted by Navy7797 View Post
Had a water temp sensor problem, guessing it was the Teflon tape. The gauge was off by 30 degree's compared to the sniper EFI ECU.. Temp gauge would only go to 150 degrees . I drilled a hole in the sensor bushing and soldered a ground wire to it, bolted other end problem solved . My painter is back working on my truck too.
JMHO, this is proof positive and contrary to some popular beliefs, the tape can indeed insulate the electrical connection or at least impede its ground conductivity (jumper wire proofing it).

There has actually been a long standing argument among some that this can NOT happen, lol. And yet, here it is, an electrical impedance of the ground connection to the sensor.
Usually, the brass threads on the sensor being tapered and soft are enough to create a good seal without any sealants required. Occasionally though if you must use a sealant it is best to use an automotive grade liquid type sealant, applied to the outside (male) threads only, ensuring a good ground connection and seal.