On coolant temp from obd2

I had ‘mechanic’ to rep my head gasket on my 2000 Tacoma prerunner. I took head to reputable machine shop for re surfacing. Machinist pointed to something on end of head next to firewall and said ‘ that’s broken’. I know now it was something to do with coolant temperature sensor cause my reading on scan gauge normall is 179 now is 40. No signal. Can’t even see what’s between firewall and back of head. Anyone have any idea what kind of connection is there. Hate to pull head off just to see. Thanks to all

 

No coolant signal to scan gauge 2

 

Coolant Temperature Sensor

can be replaced without head removed
Pretty sure deep 19mm
Need to set back the engine harness
1.5hrs took me the 1st time
2nd time took 15mins

Can cause taco to be in no start situation
Here was my 1st CTS:



Now if your pigtail is trash
Search cts replace
I know I saw a thread where member found a company that just sells the pigtail
GL