Diagnostic Alarms: Err Sfs - Pentair MT125 Installation And User Manual

Diagnostic Alarms: SFS
ERR SFS
Heater starts and runs OK,
but temperature of exhaust
climbs to 450°–500° in 3–5
minutes.
NO
Heater starts after several
tries, exhaust temperature
stays below 250°.
OR
Heater doesn't start at all
(exhaust stays cold).
Check pressure and volume
of fuel supply
OK
Disconnect the sensor and
check continuity across its
terminals. Resistance
should be 3.5-4.0 mega-
ohms.
1 = open circuit;
0 = shorted.
Does sensor check OK?
YES
Check continuity in wiring
harness between Control
Board and Probe.
YES
Continuity OK?
NO
Check the J3 and J6
connectors for corrosion/
looseness on the male
pins.
YES
Clean/tighten pins as
needed.
DONE
Reset power to Heater
and retry. Heater should
fire.
460906 Rev. D 8/2020
Check Heat Exchanger
Coil for leaks, liming, soot,
or low flow.
YES
YES
Check Thermal
Regulator: Open at
120°?
NO
Correct problem;
Heater should fire.
NO
YES
Check Thermal-Regulator:
seat s correctly?
NOT OK
Correct Fuel Supply, reset
Heater and retry. Heater
should fire correctly.
NO
NO
Replace Stack Flue Sensor
DONE
Reset power to Heater and
retry. Heater should fire.
NO
Repeat checks on fuel
supply, Thermal Regulator,
check for correct orifices,
etc.
YES
NO
Does the LCD show
Error Code "E05" or "E06" ?
NO
NO
NO
YES
(HD )
NO
(Basic)
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
Section 3. Troubleshooting
Replace Heater
Membrane Pad.
DONE
Replace Heater
Control Board.
DONE
Reset power to Heater and
retry. Heater should fire.
NO
Check Heat Exchanger Coil for
leaks, liming, soot, or low flow.
Replace Heater Control Board.
DONE
Reset power to Heater and
retry. Heater should fire.
NO
Replace Heater Membrane Pad.
DONE
Reset power to Heater and
retry. Heater should fire.
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