The other end of the wire runs to the ECU

I would not replace the sensors just the harness plug. To replace the plug just pull back the wire loom or electrical tape untell you find "soft" wire, (about 6-8 inches) next cut off the hard, brittle, wire and splice in the new plug and wire there.
the pic is an example of what you are looking to buy. This is not the right plug you want just a example.