Paloma PH2-20R OFN Engineering Handbook page 65

Check the resistance across 2 black wires
on bottom Molex:
7k – 23K Ohms
SVC 820-Tankless Gas Trouble Shooting Manual
33 – Error Code Diagnostic Chart
Is the resistance
to the Outlet
Thermistor OK?
YES
Remove Molex from Connector "R" at Control Board.
Check continuity from black #3 wire at Connector "R"
Molex and black wires at black Molex located behind
Control Board. Check continuity from red #4 wire at
Connector "R" Molex and red wire at Black Molex
located behind Control Board
Is the continuity
across all wires
OK?
YES
Attempt to operate unit again.
If the unit malfunctions due to an Error Code 33:
Replace Control Board
Clean Scale Build-Up on Outlet Thermistor.
Retest Thermistor. IF tests OK, the water
heater appears to be normal. Attempt to
NO
operate unit again. IF resistance NOT OK:
Replace Outlet Thermistor
Replace wiring harness for Connector "R"
on Control Board
NO
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