Interactive diagnostic wizard for Hayward Sense & Dispense chemistry controllers (HL-CHEM). Diagnose pH and ORP sensor faults, chemical feed issues, calibration errors, CSM communication problems, and timeout errors step by step.
Select the Check System error your controller is displaying to get step-by-step troubleshooting guidance.
Click an error or symptom to see diagnostic steps.
This interactive troubleshooting wizard is designed specifically for the Hayward Sense & Dispense (HL-CHEM) ORP and pH sensing kit. The Sense & Dispense system is compatible with OmniLogic, OmniHub, ProLogic (v3.0+), Aqua Plus (v3.0+), and AquaRite Pro controllers. It continuously monitors the pool's sanitization (ORP) and pH levels, automatically generating chlorine and dispensing pH reducer to maintain balanced water chemistry.
Select the "Homeowner" role for safe checks you can perform yourself, or switch to "Technician" mode for detailed diagnostics including voltage measurements, probe replacement procedures, and PCB troubleshooting.
| Error Code | Description |
|---|---|
| CSM Comm Error | Chemistry Sensing Module not communicating with the main circuit board |
| pH Probe Error | pH probe not detected or producing invalid readings |
| ORP Probe Error | ORP probe not detected or producing invalid readings |
| pH Low | pH reading at or below 6.9 (factory threshold, non-adjustable) |
| pH High | pH reading at or above 8.1 (factory threshold, non-adjustable) |
| pH Timeout | pH set point not reached within the configured timeout period |
| pH Calibration Error | pH probe reads more than 1.0 pH units off from calibrated value |
| ORP Low | ORP reading at or below 350 mV despite chlorine generation |
| ORP High / Chlor. Off | ORP reading at or above 950 mV; chlorinator shut off as safety measure |
| ORP Timeout | ORP set point not reached within sanitizer timeout period; chlorinator turned off |
For residential pools, clean the ORP and pH probes at least once every three months. For commercial pools, clean them every 30 days. Signs that probes need cleaning include slow response to water chemistry changes, increased need to calibrate pH, and inconsistent readings. Clean the probe tip and white reference area with a soft toothbrush and regular toothpaste or liquid dish soap, then rinse with fresh water. Always keep probe tips wet during cleaning.
First clean the probe. Then navigate to Maintenance Menu, select pH Calibration Wizard, enter your independent pH test result using the plus/minus keys, confirm the reading, and press plus to save. Always obtain test water from the flow cell chamber where the probes measure the water, not from the pool surface. Recalibrate after every probe cleaning or replacement.
CSM Comm Error means the Chemistry Sensing Module is not communicating with the main circuit board. Check the CSM cable for damage, verify it is plugged into the COMM port on the PCB, and ensure the flow cell is not exposed to direct sunlight (extreme heat can cause this error). If the cable and connections are good, measure 10-15V DC across pins 2 and 4 (black and red) on the COMM port. If no voltage, try another COMM port or replace the PCB. If voltage is present, replace the sensing module (GLX-SD-ELEC-MOD).
The flow cell requires a flow rate of approximately 1 GPM (ideal), with an acceptable range of 0.8 to 2.2 GPM. A pressure differential between the supply and return connections is needed to drive water through the cell. If flow is too low, the probes will not get fresh water samples and readings will be inaccurate.
Chlorine reducers such as Sodium Sulfite cause the ORP probe to read low. If the system is configured to auto-sensing chlorine feed, it will compensate by generating more chlorine, creating a circular pattern that wastes energy and chemicals. If you must use chlorine reducers, suspend use and monitor ORP readings. Consider switching the chlorine feed mode from auto-sensing to timed percentage temporarily.
Yes. Select the "Homeowner" role and the wizard will show only the checks that are safe and practical for a non-professional to perform. Technician-level steps such as voltage measurements, PCB diagnostics, and probe replacement are hidden unless you switch to Technician mode. Always follow the safety warnings and consult a licensed pool service professional for any repair you are not comfortable performing.
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