Replacement Heater Thermistor 420010053S This replacement thermistor restores accurate temperature sensing in compatible pool and spa heaters. It is a directfit replacement for part numbers 420010063S and STA1516255 and is intended for use in compatible heater models. Key benefits Restores temperature sensing: Replaces a failed or inaccurate thermistor so the heater can read temperature correctly and resume normal operation. Directfit replacement: Designed to match the electrical and mechanical connection of the original part numbers 420010063S and STA1516255 for straightforward installation. Reliable performance: Precision sensing element provides consistent feedback to the heater control, reducing false error codes related to temperature sensing. Saves time on repairs: Swapping the thermistor eliminates the need for complex diagnostics when a faulty sensor is suspected. What it does Functions as the temperature sensing element inside the heater control system. Communicates the water or combustion chamber temperature to the heater control board so the system can regulate heat output. Compatibility and fit Compatible with MasterTemp and StaRite MaxETherm heater models where part numbers 420010063S or STA1516255 are specified. Identified by manufacturer part number 420010053S as the replacement thermistor for the listed part numbers. Practical attributes Form factor: Compact sensor assembly designed for the heater environment and to fit the original mounting and connector layout. Installation: Plugandplay style replacement for quick swap during maintenance or . Durability: Built to withstand typical heater operating conditions and repeated service interventions. Use scenarios Onsite after the heater displays a or low temperature fault: the thermistor to clear the fault and restore heating operation. Preventive maintenance for seasonal startup: Fit a thermistor to avoid midseason failures and reduce service calls. Service technician spare part: Carry the replacement thermistor for rapid diagnostics and sameday repairs on compatible heater models. What to check before Verify that your heater lists part number 420010063S or STA1516255 in the parts list or service manual. Confirm connector type and mounting location match your existing sensor to ensure a direct replacement. This thermistor replacement is intended to match the original temperature sensing function for the listed part numbers and compatible heater models.