Sensors live in harsh places. Engine-bay connectors see heat, vibration, oil, coolant, water and cleaning chemicals. Underbody sensors see road salt, stones and flexing harnesses. A sensor located near an exhaust component may experience extreme thermal cycling.
Connector faults include backed-out terminals, poor terminal tension, bent pins, corrosion, water intrusion and broken locking tabs. Wiring can fail internally while insulation still looks intact, especially near hinge points, engine mounts, exhaust heat or previous repair areas. Rodent damage is another real source of intermittent sensor faults.
Visual inspection should be targeted, not ceremonial. Follow the harness from the sensor toward the module and look where movement, rubbing, heat and water are likely. Gently tug suspect wires near terminals. Compare pin height and terminal appearance. If a fault changes when the harness is moved, you have useful evidence but still need to isolate the exact point.
Repair wiring with appropriate automotive methods and sealing. Twisting wires together and covering them with household tape is not a durable diagnostic repair.