Bosch C 1210 ES Installation Manual page 53

Display Cause
Ionization failure during operation.
Internal hardware/software failure.
Ionization error at standby.
Gas leakage error, gas valve circuit
not closing properly.
Table 29
6 720 644 887
Solution
Fig. 2 page 6
1. Check gas type, ,
2. Check three wire connections to ignition group on the lower
front of the heat exchanger are secure.
3. Verify that venting specifications are met. Improper venting may
cause premature failure of the flame sensor rod. See
page 10
.
4. Check gas pressure. See
5. Check and adjust CO readings. See
2
6. Check that the minimum power fan speed has been adjusted to
page 21
the proper value. See
1. Disconnect power supply cord and check the two wire and
ground connections on control board as well as ground connection
on heater chassis.
2. Pressing the wrong combination of buttons on the control unit
can create confusion among the microprocessors inside. In this
case, the error code should not happen more than once or twice.
Turn off the water heater. Turn water heater back on and try
resetting error code. Use the reset button (
codes.
3. Possible defective control unit call Bosch Water Heating for
further instructions.
1. Loose connection to the flame ionization rod. Verify that the
thinner wire leading from the control unit is securely connected to
the set of electrodes located on the lower front of the heat
exchanger.
2. Flame ionization rod or control unit may be damaged. Contact
Bosch Water Heating for further instruction.
1. Disconnect power supply cord and check wire connections on
gas valve and the two connectors on the control board.
2. Loose connection to the flame ionization rod. Verify that the
thinner wire leading from the control unit is securely connected to
the set of electrodes located on the lower front of the heat
exchanger.
3. Gas valve may be defective, contact Bosch Water Heating for
further instrucation.
Error codes
.
chapter 3.3
chapter 3.14, page 35.
chapter 6.5, page 42.
.
) to reset any error
,
53