Problem Solving; Error Code Diagnostics - Bosch Greentherm T9800 SEC 199 Installation And Operating Instructions Manual

60 | Problem solving

9 Problem solving
9.1

Error code diagnostics

To remove error codes from the display,
▶ Touch the On/Off button more than 3
sec. (long press).
Display Description
A0 Water temperature sensors [17] [19] [20]
disconnected or damaged.
A1 Air temperature inside the cabinet [18] is above
158 °F. Appliance regulates power to protect
against overheat.
A2 External water temperature sensor/aquastat [21]
disconnected, damaged or not properly installed.
A3 Flue gases temperature sensor [15] disconnected
or damaged.
A4 Air temperature sensor [18] disconnected or
damaged.
A5 Condensing unit flue temperature sensor [16]
disconnected or damaged.
A6 Inlet cold water temperature sensor [20]
disconnected or damaged.
A7 Heat exchanger hot water temperature sensor
[16] disconnected or damaged.
A8 Outlet hot water temperature sensor [17]
disconnected or damaged.
A9 Incorrect output power (too low).
Table 27
6 720 816 815 (2018/08)
Installation, maintenance and repair must only be carried out
by qualified contractors. The following table describes the
solutions for possible problems.
Solution
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ External air temperature is above 140 °F.
▶ Check for flue leakages inside the appliance or in
concentric vent.
▶ Check temperature sensor and associated
1) 2)
connections.
▶ Check sensor position in the tank pocket.
▶ Verify if correct recirculation settings are in use
(section 6.5.2).
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check sensor wire connections.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check connections or replace sensor.
▶ Replace the sensor and/or wire connections, if the
problem persists.
▶ Check gas inlet pressure
▶ Check water temperature sensors [17][19][20]
and water flow sensor [14] wire connections.
▶ Check sensors resistance and water flow sensor(
section 11) and replace any if it is not according to
1) 2)
specification.
Greentherm T9800 SE 160/199 | SEC 199
1) 2)
1)
1)
1)
1) 2)
1)
1) 2)
1)
1) 2)
1)
1) 2)
1)
1) 2)
1)
1) 2)
1)
1)
( section 4.13).