Bosch boiler faults: fault codes, causes and parts (page 2 of 3)

Codes 151 to 300 of the 377 fault codes for Bosch. Looking for a specific code? Use the search on the first page.

Bosch boiler fault codes 151 to 300 of 377

The code list is split over 3 pages. Looking for a specific code? Use the search on the first page: it searches all 377 codes in one go.

Code	Cause
B2U565	The difference between flow and return temperature is too large > 60K.
B2U565	The difference between flow and return temperature is too large >60K.
B5L542	Incomplete communication with the burner control unit
B5L542	Incomplete communication with the burner control unit.
B5L543	No communication with the burner control unit
B5L543	No communication with the burner control unit.
B6A577	No flame within the safety time
B6L514	Flame interruption within the flame stabilisation time.
B6L515	Loss of the ionisation signal during operation.
B6L515	Loss of the ionisation signal during operation
B7A550	Undervoltage
B7A551	Power interruption
B7P549	The safety circuit is open
B8L579	No gas supply pressure
B8U584	Changeover module no feedback
C1	Pressure switch open during operation.
C1	Fan speed too low. .
C1	Fan speed too low.
C1	Pressure switch is open during operation.
C1264	The control signal or the voltage of the fan has been lost during operation.
C4	Pressure switch does not open during standstill periods.
C4	Pressure switch does not open in the idle state.
C4273	The boiler has been switched off for a maximum of 2 minutes because the boiler has been in continuous operation for 24 hours. This is a safety check.
C6	Pressure switch does not close.
C6	Fan does not run.
C6	Pressure switch does not close.
C6215	The fan is running too fast.
C6216	The fan is running too slowly.
C7214	Fan does not run during the start-up phase [0/c/\\|.
C7217	The fan runs irregularly during start-up.
CA	Turbine defective.
CA	Flow meter (turbine) defective.
CC	Outdoor temperature NTC not recognised.
CC	Outdoor sensor of a TA 211 E has an open circuit.
CC	Outdoor temperature sensor not recognised.
CC	Outdoor sensor of a TA 211 E has an open circuit
CC	Outdoor temperature sensor not recognised.
CE207	The heating water pressure is too low, lower than 0.8 bar.
CE267	After four attempts the pressure sensor has been unable to measure sufficient pressure rise (water flow) on the heating side. This check is repeated approx. every 5 min until sufficient pressure rise on the heating side is measured.
CE329	The pressure sensor measures insufficient pressure rise (water flow).
CF288	The water pressure is too high (> 5.7 bar) or the contacts of the pressure sensor are open-circuit.
CF289	The contacts of the pressure sensor are short-circuited.
CF350	The contacts of the flow temperature sensor are short-circuited.
CF351	The contacts of the flow temperature sensor are open-circuit.
D1	LSM in lockout.
D3	Jumper 8-9 not recognised.
E0	Internal error.
E0	Module error.
E0	Internal error on PCB.
E2	Flow NTC has an open circuit or short circuit.
E2	Flow NTC defective.
E2	Flow NTC fault
E2	Flow temperature sensor defective.
E2222	The contacts of the flow temperature sensor are short-circuited.
E2223	The contacts of the flow temperature sensor are open-circuit.
E3347	The return temperature sensor has measured a higher central heating water temperature than the flow temperature sensor. A restart follows after 10 minutes.
E5	The flow temperature is > 100°C.
E5	Burner temperature sensor temperature exceeded.
E7	Burner temperature sensor is open-circuit or short-circuited
E7	Burner temperature sensor is open-circuit or short-circuited.
E9	Safety temperature limiter has been activated.
E9	Temperature limiter in the heat exchanger or flue gas temperature limiter has switched off.
E9	The maximum protection of the heat exchanger is activated when the temperature rises above 105°C.
E9	Temperature limiter in flow has been activated.
E9	Heat exchanger maximum thermostat or flue gas maximum thermostat has tripped.
E9	Temperature limiter in flow has switched off.
E9224	The maximum or burner thermostat has measured too high a temperature and is open.
E9276	The flow temperature sensor has measured a temperature higher than 95 °C.
E9285	The return temperature sensor has measured a temperature higher than 95°C.
E9316	The flue gas sensor has measured too high a temperature.
E9318	The contacts of the flue gas sensor are open-circuit.
EA	Flame not detected (no ionisation).
EA	The burner does not ignite.
EA	Flame not detected.
EA	No ionisation current.
EA227	Insufficient ionisation current has been measured after the burner ignited.
EA229	Insufficient ionisation current has been measured during burning.
EA234	The contacts of the gas valve are open-circuit.
EA261	The burner control unit is defective.
EC256	The burner control unit or the KIM is defective.
EC346	The temperature of the flue gas sensor rises too quickly.
EE348	During hot water mode: the flow temperature is higher than 85 °C.
EF345	The flow temperature sensor measures no temperature rise after a burner start.
EF349	The temperature difference measured at low load between the flow temperature sensor and the return temperature sensor is too large.
EH258	The burner control unit or the KIM is defective.
Ed343	During heating mode: the temperature of the flue gas sensor rises, but the temperature of the flow temperature sensor does not.
Ed344	During hot water mode: the temperature of the flue gas sensor rises, but the temperature of the flow temperature sensor does not.
F0	Internal error.
F0	Internal fault.
F0237	The burner control unit or the KIM is defective.
F0238	The burner control unit or the KIM is defective.
F0239	The burner control unit or the KIM is defective.
F0246	The burner control unit or the KIM is defective.
F0250	The burner control unit or the KIM is defective.
F0251	The burner control unit or the KIM is defective.
F0252	The burner control unit or the KIM is defective.
F0253	The burner control unit or the KIM is defective.
F0254	The burner control unit or the KIM is defective.
F0259	The burner control unit or the KIM is defective.
F0262	The burner control unit or the KIM is defective.
F0263	The burner control unit or the KIM is defective.
F0272	The burner control unit or the KIM is defective.
F0279	The burner control unit or the KIM is defective.
F0280	The burner control unit or the KIM is defective.
F0290	The burner control unit or the KIM is defective.
F1	Internal data error.
F1	Internal data error.
F7	Flame is detected although the boiler is switched off.
F7	Incorrect ionisation signal.
F7	Flame is detected although the appliance is switched off.
F7	Flame is detected although the boiler is switched off.
F7228	An ionisation current was measured before the burner started.
F7306	An ionisation current was measured after the burner was extinguished.
F7328	There has been a brief interruption of the mains voltage.
F9	Defect in the electrical circuit of the gas valve.
FA	Flame is detected after gas shut-off.
FA	After gas shut-off: flame is detected.
FA	Ionisation current persists after control shut-off.
Fd	The reset button was pressed by mistake.
Fd	The reset button was pressed by mistake.
Fd	Reset button was pressed accidentally.
Fd	The reset button was pressed although the reset button was not illuminated.
Fd231	The mains voltage was interrupted during a lockout fault.
H031013	Operating hours elapsed
H061016	Frequent flame interruptions
H07	The measured heating water pressure is too low. The output for both heating mode and hot water mode is limited.
H071017	Water pressure too low
H081018	Service time elapsed
I--I	Calibration of the NTC sensor (see manual page 33).
OA	Appliance in switching optimisation programme
OA-	Appliance in switching optimisation programme
OC	Start of burner start
OC-	Start of burner start
OE	The appliance is in standby, heat demand is present but too much energy is being supplied.
OE-	The appliance is in standby, heat demand is present but too much energy is being supplied.
OF	Insufficient flow through the boiler
OF-	Insufficient flow through the boiler
OH	The appliance is in standby, no heat demand present.
OH-	The appliance is in standby, no heat demand present.
OL	Opening of the gas valve
OL-	Opening of the gas valve
OP	Waiting for fan to start
OP-	Waiting for fan to start
OU	Start of the burner start programme
OU-	Start of the burner start programme.
OY	The actual heating water temperature is higher than the desired boiler water temperature.
OY-	The actual heating water temperature is higher than the desired boiler water temperature.
P1, P2, P3, P1..	Please wait, initialisation.
P1, P2, P3, P1…	Initialisation has not taken place. .
P1, P2, P3, P1…	Please wait, initialisation.

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