Error Code 66 (Rtg66 Only); Error Code 71; Error Code 72 - Rheem RTG2-42 Troubleshooting Manual

Yes
When motor
operates, is the
voltage to the
water control
OK?
Replace the Water Control Assembly

Error Code 66 (RTG66 Only)

Error Code 71

Explanation: Gas Inlet Solenoid Valve (G.I.S.V) fault. Check gas inlet solenoid valve wiring
harnesses for loose or damage terminals; and connection K to the circuit board is tight.
Is there power
to the G.I.S.V.
valve?
Yes
Replace G.I.S.V. Valve

Error Code 72

Explanation: Flame Sensing Device fault. The Flame Probes are sensing the presence of flame
when there is not suppose to be any flame.
See and follow the same procedure as used in Error Code 51.
No
Replace the Printed Circuit Board
Measure the voltage at connector B between the White#2 and
Black#8 wires for: 8 to 16 VDC
No
Replace the Printed Circuit Board
With the unit attempting to go to main burner, measure the voltage
at connector K between the Yellow and Black wires for:
75 to 100 VDC
60
SVC 810 Tankless Troubleshooting Manual