Exact replacement sensor for Pentair MasterTemp and Sta‑Rite Max‑E‑Therm heaters Replaces Part No. 420020024S for Pentair MasterTemp pool and spa heater electrical systems. Also fits Pentair Sta‑Rite Max‑E‑Therm pool and spa heater electrical systems, models SR200, SR333, SR400. Key benefits — why you need this sensor Restores correct temperature sensing and heater operation after a failed or degraded sensor. Prevents overheating by limiting flue gas temperatures to safe levels, protecting internal components and reducing risk of shutdowns or damage. Stops common errorcode faults so your heater runs reliably: corrects E02, E05 and E06 error messages. Primary functions and performance Temperature protection: prevents flue gas temperatures from exceeding 500°F. Operating range: 20°C to 105°C. Designed to the original factory sensor and the heater to intended performance and safety limits. Material and durability Stainless steel construction provides corrosion resistance for long service life in pool and spa environments where exposure to moisture and chemicals is common. Compatibility and fit Exact replacement for Part No. 420020024S. Compatible with Pentair MasterTemp pool and spa heater electrical systems and Pentair Sta‑Rite Max‑E‑Therm systems, models SR200, SR333, SR400. Use this part when replacing the factory sensor in these specified systems. Practical use scenarios 1. Repairing a heater that displays E02, E05 or E06 error codes: the faulty sensor to resolve the error and restore normal ignition and temperature control. 2. Routine maintenance during offseason service: swap in a corrosionresistant replacement sensor to maintain accurate temperature monitoring and extend heater life in a pool or spa environment. 3. Protecting a use pool heater from overheating: install this sensor to ensure flue gas temperatures stay within safe limits and prevent component stress or forced shutdowns. What makes this part stand out Factoryequivalent replacement that matches the original part number and intended function. Durable stainless steel construction suited for the humid, chlorinated conditions around pools and spas. Targets the exact error codes and overheating conditions common to the supported heater models. Note: Use this sensor specifically for the listed Pentair MasterTemp and Sta‑Rite Max‑E‑Therm models to ensure compatibility and correct system operation.