Bosch boiler error codes

German technology has earned an excellent reputation. And the fact that today Bosch boilers are assembled in Bulgaria has no effect on the products` quality. The technology and principle of assembly have remained the same. Reliability and duration of the Bosch boilers is also provided by the failure detection system. Below you can find the table of Bosch error codes.


DISPLAYDESCRIPTIONELIMINATION
A7DHW temperature sensor defective.* Check temperature sensor and leads for interruptions or shorts, and replace if defective.
* Insert code plug correctly; replace if defective.
A8Communication fault.* Check BUS communications wiring, replace if defective.
* Check control, replace if defective.
AdDHW tank temperature not detected.* Check DHW tank temperature sensor and connecting lead, replace if defective.
The DHW tank temperature sensor was recognized before the connection was lost.* Reset the boiler to the factory default settings, reset the IPM 2 (if installed) to the factory default settings and carry out the automatic system configuration.
blCode plug not detected.* Insert code plug correctly; replace if defective.
b2/b3/
b4/b5/
b6
Internal data error.* Reset boiler to factory default setting.
b7Fault in the burner controls.
C6Fan not running.* Check fan leads and fan, replace if defective.
CCOutdoor temperature sensor not recognized.* Check outdoor temperature sensor and leads for interruptions, replace if defective.
* Verify the outdoor temperature sensor is connected to terminals A and F.
d3Temperature high limit defective. External guard has tripped. Temperature limiter locked out.* Check temperature sensor and leads for interruptions or shorts, and replace if defective.
* Temperature guard TB1 has tripped. Check if jumper across 8-9 or PR-PO is missing.
* Reset external temperature limiter (if installed).
* Reset LWCO (if installed).
d5External supply temperature sensor defective (low-loss header).* Check temperature sensor and leads for interruptions or shorts, and replace if defective.
The external supply temperature sensor was recognized on the BUS and then reconnected to the appropriate terminal.* Check whether only one temperature sensor is connected; otherwise remove second temperature sensor.
* Reset the boiler to the factory default settings, reset the IPM 2 (if installed) to the factory default settings and carry out the automatic system configuration.
E2Supply temperature sensor defective.* Check temperature sensor and leads for interruptions or shorts, and replace if defective.
E3Additional supply temperature sensor defective.
E9Heat exchanger safety high limit or flue gas temperature limiter has tripped.* Check flue gas safety high limit and leads for interruptions or shorts, and replace if defective.
* Check heat exchanger safety high limit and leads for interruptions or shorts, and replace if defective.
* Check the operating pressure.
* Check temperature limit; replace if defective.
* Check pump capacitor; replace pump if defective.
* Check PCB fuse, replace if blown (6.3 A fuse according to IEC default).
* Purge the appliance
* Check heat exchanger on the DHW side; replace if clogged.
EANo flame detected.* Check that ground lead is properly connected, replace if defective.
GFA: Safety time expired.* Check that gas cock is open.
* Check inlet gas pressure; correct if needed.
* Check power supply.
* Check electrodes for visual damage; replace if defective.
* Check flue gas system; clean or repair if defective.
* Check gas/air ratio; correct if out of range.
* Check gas valve; replace if defective.
* In room air operation, check air supply or ventilation apertures.
* Clean the condensate trap.
* Remove diaphragm at fan inlet connection and check for contamination or cracks.
* Check heat exchanger for soiling
* Check gas cock; replace if defective.
* Insert code plug correctly; replace if defective.
FOInternal fault* Press reset for 3 seconds and release. When the button is released, the appliance will restart.
* Check electrical plug-in contacts and ignition leads; replace PCB if defective.
* Check gas/air ratio; correct if out of specification.
FIInternal data error.* Reset boiler to the factory default setting.
F7Flame detected even when burner is off.* Check electrodes; replace if defective.
* Check flue gas system; clean or repair if defective.
* Check PCB for moisture; dry if needed.
FAAfter switching gas off: Flame is detected.* Check gas cock; replace if defective.
* Clean condensate trap.
* Check electrodes and leads; replace if defective.
* Check flue gas system; clean or repair if needed.
FdReset button pressed by mistake.* Press reset button again.
* Check cable harness to safety high limit and gas cock for ground connection.