Begin with the heater model, displayed message and operating conditions. Gas pressure, combustion, voltage and safety-switch tests belong to a qualified heater technician.
Stop immediately for these conditions
If you smell gas, do not attempt ignition or operate electrical switches; leave the area and contact the gas supplier or emergency service from a safe location. Do not restart a flooded heater, or continue using equipment with soot, scorching or abnormal combustion.
Collect the operating picture
- Photograph the complete model/fuel label and exact display code. Note whether the display is dark, calls for heat, shows an error or starts and stops. Record water temperature and requested setpoint.
- Check the selected pool/spa mode and automation schedule from the normal controls. Confirm circulation is established and note current pump RPM, filter pressure and return flow.
- Observe whether externally accessible air openings are obstructed without removing panels or touching the flue. Do not assume the fault is a failed board just because a light is on.
Interpret codes in the right manual
The MasterTemp manual separates water pressure, air flow, high-limit and other alarms; the same letters on another brand may mean something different. A pressure-related fault warrants a flow-system assessment, not a jumper wire. Never bypass the water-pressure switch, reset a rollout device as a workaround or conduct live terminal tests.
Make the service request specific
Send label and display photos, exact symptom sequence, pump/filter observations and when it last worked. Ask the technician to verify the cause and confirm safe operation after repair rather than approving a speculative part swap.
Sources and scope
Documentation checked October 11, 2026. Manufacturer examples apply only to the named equipment; confirm your model and revision. This is homeowner assessment and planning guidance, not a claim that your equipment has been inspected.
- Pentair: MasterTemp installation/user guide — Safety; installation; printed pp. 42–55: operation and diagnostics
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