Vaillant 193592 Sensor NTC (CH flow/CH return)

The Vaillant 193592 is an NTC sensor that monitors temperature on the central heating flow and return circuits. It is a Vaillant spare part, catalogued under thermostats, thermistors and sensors, and sits within the appliance to report water temperature back to the control board. That temperature data drives the boiler's modulation and its internal safety logic, so the sensor needs to read accurately for the appliance to run as intended.

• The boiler locks out or refuses to fire, with the fault returning after a reset.
• Flow or return temperature readings that drift from the actual pipe temperature, or that sit at an implausible fixed value.
• Heating output that hunts up and down, or radiators that never reach temperature despite the boiler running.
• Intermittent fault codes relating to temperature sensing or flow and return temperature difference.
• Short cycling, where the burner fires and cuts out repeatedly over a short period.

• Confirm the part number on the existing sensor matches 193592 before ordering.
• Check the appliance serial and GC number against the compatibility list to confirm the correct variant.
• Inspect the sensor seal or O-ring at the pocket while the sensor is out and renew it if it shows signs of hardening or perishing.
• Allow the system to cool and isolate the appliance before removing the sensor from its pocket.