Pentair MT125 - Error and Fault Codes

460906 Rev. D 8/2020 MASTERTEMP 125 Pool and Spa Heater Installation and User’s Guide
49
Error and Fault Codes
Table 8. Heater Error and Fault Codes
Fault Condi�on
Error Code
Displayed
Note
Troubleshoo�ng
Water pressure switch
open
ERR PS
If water ow is established the
the error is cleared and normal
operaon is resumed.
No water ow thru
heater
Hi temperature limit
switch open
ERR HLS
When the temperature falls
below 135°F the error is cleared
and normal operaon is
resumed.
Water temperature aer
the 1
st
pass through the
heater exchanger is more
than 135°F.
Air ow switch open
ERR AFS
If adequate air ow through the
blower is established within 60
seconds the heater will resume
normal operaon. If the error is
not corrected within 60 seconds
the heater will need to turned
o by pressing the HEATER OFF
buon.
The blower is not on or
air thru it is being
restricted
Ignion Control Module
ERR IGN
To clear the error the HEATER
OFF buon must be pressed.
The Ignion Control
Module was not able to
ignite the heater.
Automac gas shuo
ERR AGS
The front panel buons will be
disabled. To reset the heater,
cycle power.
Water temperature aer
the 2
nd
pass thru the heat
exchanger is more than
140°F
Excessive stack ue
temperature
ERR SFS
The front panel buons will be
disabled. To reset the heater,
cycle power.
The temperature of the
stack ue is more than
480°F
Open stack ue sensor
E05
Shorted stack 
sensor
E06
The front panel buons will be
disabled. To reset the heater,
cycle power.
Follow diagram on page
53/54
Open water
temperature sensor
E01
To clear the error the HEATER
OFF buon must be pressed.
Follow diagram on page
53/54
Shorted water
temperature sensor
126
Follow diagram on page
53/54
Follow diagram on page
55
Section 3. Troubleshooting