Diagnostic Flash Codes; Flashes (Led Not Lit); Status Light On (Solid); Flash - A.O. Smith GCV300 Service Handbook

7. Wait 10 minutes and try to light the
Pilot according to the instructions
on the water heater's label.
8. While clicking the igniter button
continuously, the control knob must
be set to Pilot and held in until the
Status Light blinks. Once the status
light blinks, release the control knob
and set the knob to the desired
temperature setting.
approximately 120°F.)
Diagnos c Flash Codes
NOTE: In each case, the flash code will
occur, followed by a 3 second pause,
and then will repeat.

0 Flashes (LED not lit)

Indication/Condition:
Control Off/Pilot Out.
Check/Repair:
1. Follow the lighting instructions on the
front of the water heater and attempt
to relight the pilot. Confirm that
the pilot is lit by looking through the
viewport (Figure 16, p. 17).
2. If pilot will light but does not
hold, check for a tripped thermal
switch. (Measure continuity by
placing a meter lead on each of
the two terminals.
means that it was not tripped.) If
thermal switch is tripped, check for
flammable vapors in the area and
ensure that the unit has adequate
combustion air and proper draft
before relighting. (You can reset
the thermal switch by pressing the
reset button in its center.) Also,
ensure that the filter and flame
arrestor are clean (p. 18).
3. If the pilot will light and does hold,
record any status codes and follow
the procedures relating to that code.
4. If pilot will not light at all, verify the
piezo igniter is producing a spark
and the unit is getting the correct
supply gas pressure. See "Testing
10 • Residential Standard Gas Water Heater Service Handbook
the Igniter
"Gas Pressure Checks" (p. 11).
Also, check the thermopile wiring
connections (Figure 16, p. 17).

Status Light On (solid)

Indication/Condition:
Pilot light was recently extinguished
and the thermopile is cooling down.
("Hot" is
Check/Repair:
1. Turn
thermostat knob to OFF.
2. Wait 10 minutes for the thermopile
to cool, then attempt to relight
the pilot by following the lighting
instructions on the water heater's
label. NOTE: This gas control valve/
thermostat has built-in circuitry
that requires waiting 10 minutes
between lighting attempts.
Until the Thermopile reaches its
normal operating temperature,
the status light will not blink, even
if the pilot is lit. It may take up to
90 seconds of continuous pilot
operation before the thermopile
reaches
temperature and the Status Light
starts to blink.

1 Flash

Continuity
Indication/Condition:
Normal
heartbeat)
Check/Repair:
necessary.

2 Flashes

Indication/Condition:
Thermopile voltage low.
Check/Repair:
1. Check all wiring connections for loose
or damaged wires. Correct if needed.
2. Check the millivolt output on the
thermopile. If output is less than 350
millivolts DC, replace the thermopile.
See also "Condensation" on page 15.
System" (p. 19);
the gas control valve/
normal operating
Operation (bright/dim
No corrective action
4 Flashes
Indication/Condition:
Temperature exceeded (ECO activated).
Check/Repair:
1. Turn gas control valve/thermostat
knob to OFF.
2. Turn the main gas supply OFF.
3. Replace the gas control valve/
thermostat.
5 Flashes
Indication/Condition: Sensor failure.
Check/Repair:
1. Turn gas control valve/thermostat
knob to OFF.
2. Turn the main gas supply OFF.
3. Replace the gas control valve/
thermostat.
7 Flashes
Indication/Condition:
Internal control failure.
Check/Repair:
1. Turn gas control valve/thermostat
knob to OFF.
2. Turn the main gas supply OFF.
3. Replace the gas control valve/
thermostat.
8 Flashes
Indication/Condition: Power off failure.
Check/Repair:
1. If the pilot flame is present when
the control knob is set to the OFF
position, replace the gas control
valve/thermostat.
2. If the pilot flame is not present when
the control knob is set to the OFF
position, wait 10 minutes for the
thermopile to cool, then relight the
unit. If this condition returns, replace
the gas control valve/thermostat.