Hayward FDXLTER1930 FD Series Thermistor - HS Error

Hayward FDXLTER1930 FD Series Thermistor – HS Error Fix

Getting an HS (High Sensor) error on your Hayward H-Series pool heater? The FDXLTER1930 thermistor is the most common cause. This genuine OEM replacement part senses inlet water temperature in the manifold adapter and controls burner operation — when it fails, your heater throws an HS fault and shuts down.

When the inlet water temperature drops below your set point, the burner controller supplies power to the combustion air blower through a series of safety interlocks to bring your water back up to temperature. A faulty thermistor breaks this cycle — replacing it restores normal heater operation.

Compatible Models

Suits Hayward Universal H-Series Low NOx Pool Heaters:

• H150FDN / H150FDP
• H200FDN / H200FDP
• H250FDN / H250FDP
• H300FDN / H300FDP
• H350FDN / H350FDP
• H400FDN / H400FDP

Product Specifications

• Part Number: FDXLTER1930
• SKU: 20-FDXLTER1930
• Brand: Hayward (Genuine OEM)
• Series: FD / Universal H-Series
• Function: Inlet water temperature sensor / thermistor

Frequently Asked Questions

What does the HS error mean on a Hayward heater?

The HS (High Sensor or Header Sensor) error indicates a fault with the inlet water temperature thermistor. The heater cannot confirm safe water flow or temperature, so it shuts down as a safety measure. Replacing the FDXLTER1930 thermistor typically resolves this fault.

Is this a genuine Hayward part?

Yes — the FDXLTER1930 is a genuine OEM Hayward replacement part, ensuring full compatibility with your H-Series heater.

Download Installation and Maintenance Manual (PDF)