Temperature gauge bouncing around after 20-30 minutes driving. Needle goes from normal operating temp to cold when accelerating, then returns to normal during idle or flutters between cold and normal.
Replacing the engine coolant temp sender (37750-PH2-014). Tech saying connector wires are brittle and telling me to replace the cabin wire harness (32100-ST7-A82)? This seems like overkill. Wondering if just the sender wire branch harness can be replaced instead? Having trouble finding compatible parts. Closest I could find is Dorman 85140 — 1-Wire Coolant Temp Sensor Pigtail. Not sure if this would actually work?

 

It may or may not be due to the wiring. It can also be due to something with the gauge cluster.

The Yel/Grn wire from the sender runs through various harness connectors before it gets to the gauge; so, just throwing parts (sender, cabin wire harness) may not solve the issue.

If it really was just due to the wire; it would be easier and less costly to just splice a new wire from the sender to the wire going into the temperature gauge.