Honeywell Temperature sensor SO11013

This Honeywell temperature sensor (SKU SO11013) is an NTC (negative temperature coefficient) immersion probe used in heating and hot water systems. Its resistive NTC sensing element measures coolant temperature and sends a resistance signal to the boiler control system. It is designed for Baxi boilers and compatible thermal equipment. The immersion probe form provides fast response to temperature changes and high measurement accuracy. The sensor remains stable under constant temperature loads.

When selecting a replacement of this kind, the critical parameter is the resistance at a reference temperature—commonly 10 kΩ or 12 kΩ at 25 °C—which must match the control board's firmware. The mechanical form must suit the installation: immersion, clamp-on, or sleeve. Cable length and connector type must also match the existing harness. After fitting, verify the probe is clean, properly seated, and check the reading against a reference thermometer.

When sensors of this kind fail, the usual mode is a drifting resistance characteristic, which makes the sensor report incorrect temperatures and leads to poor burner modulation or short-cycling. A broken cable or poor thermal contact between a probe and the pipe causes erratic signals. Check wiring continuity and the probe's thermal contact, and compare the sensor output with a reference thermometer at a known temperature.