Coyote Gen 2 Engine Harness/Sensors?

New Ford Performance Coyote Gen 2 crate engine. The wiring harness has a single wire (purple) with connector at the rear of the engine that splits out of the main harness and it is not connected to any sensor.

Ford Instruction Sheet M-6017-M504 page 10, Figure 2 is incorrect. It labels this as C1164 Cylinder Heat Temperature (CHT) Sensor. The CHT is located on the RIGHT head. Note this forum has addressed this in other posts.

Reference is photograph of the new crate engine showing the wire/connector not connected to anything. To the lower left of the wire is the LH exhaust CMP sensor. To the upper right of the wire is the LH intake CMP sensor.

A second photo of a used engine with this wire connected to something. What is it?