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HAYWARD UNIVERSAL H-SERIES LOW-NOX Error Code

CONF DIAGNOSIS ACTION
90%
CONF
Water Pressure Switch
The 'LO' code indicates the safety circuit for water flow is open. This switch uses a diaphragm to sense back-pressure from the pump; if the diaphragm ruptures or the internal microswitch fails due to corrosion, the heater cannot confirm water flow and will prevent ignition to protect the heat exchanger.
SKU: FDXLPSW1930
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10%
CONF
High Limit Switch Kit
The 'LO' error path in H-Series circuitry sometimes involves the high-limit thermostats. If these thermal discs trip or lose continuity due to scale buildup on the heat exchanger, they break the safety loop, resulting in a limit-related fault code.
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DIY Repair Guide

Watch exactly how to replace the Water Pressure Switch.

// NOTICE: This report is generated by an Agentic AI Engineer utilizing probabilistic modeling.

PartSniper is an automated parts recommender service. AI-generated results may not be correct. This data is not a substitute for professional engineering advice or manual inspection. Always verify part compatibility and disconnect power before any repair. PartSniper is not liable for inaccuracies, injury, or damage.

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