Problem Solving; Error Code Diagnostics - Bosch Therm C 1210 ES Installation And Operating Instructions Manual

Problem solving

9 Problem solving
9.1

Error code diagnostics

To remove error code from the display, press the reset button.
Display Cause
Fault in the flue gas limiter.
Temperature above 230°F
(110 °C) inside the cabinet.
Wire harness defect.
Backflow temperature sensor
defect - happens if sensor is
disconnected or short circuit.
Outlet temperature sensor fault
(Temperature below 36°F or above
210°F).
(Flashing) Outlet temperature sensor not
sensing expected output
temperature.
(Status message, not an error).
60
Solution
1. Check continuity of the flue gas limiter (see fig. 74, page 69). Go to steps two
and three to determine flue gas limiter fault and repair it.
2. Check for flue gas leakage around the top and bottom seals of heat
exchanger, use mirror to check around the rear as well as the viewing window.
3. Check that flue gas limiter connector and spade connections are secure.
4. Unplug heater and check the wiring harness connections on the control
board.
1. Check wire harness. See fig. 81, #7, page 81.
2. Measure resistance loose on wire harness nearby the overmolding, must be
115-120 ohm.
3. Check diagnostic menu > 1P, "nC" must be showed on the display.
1. Check backflow temperature sensor connection. See fig. 74, #1, page 69.
2. Replace exhaust temperature sensor.
3. Check sensor (ref. page 65, chapter 11).
1. Check wire connection at hot water temperature sensor. See fig. 80,
page 79.
2. Sensor may trip if water temperature drops below 36°F to protect heater
from freezing conditions. Any damage due to freezing conditions is not covered
under warranty.
3. In areas where water has a high mineral content, periodic descaling may
necessary.
4. Check sensor (ref. page 65, chapter 11).
1. Check wire connection at hot water temperature sensor, see fig. 80,
page 79.
2. Check gas pressure. Low gas pressure may prevent the heater from reaching
desired output temperature.
3. Check supply voltage. It must be 120VAC and properly grounded.
4. Possible defective control unit call Bosch Water Heating for further
instructions.
C 1210ES/ESC – 6 720 644 887 (2022/04)