- Boilers
- Gas boiler
1019
Junkers 1019 gas boiler: incorrect pump type detected
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Condens 4300iW warning 1019 means an incorrect pump type has been recognised. Save the display message and any recent pump replacement record; a technician must check the pump identity and its wiring.
Safety first
Stop and check this first
- Should a gas smell accompany 1019, stop checking the pump warning and leave without using indoor phones, doorbells or electrical switches. Avoid flames and sparks, isolate gas and ventilate only if safe, keep people out and contact the emergency services and gas supplier from outdoors.
Safe checks you can perform
- Save the pump identification warning
- Find any recent pump replacement record
- Check pump type and connections professionally
Leave these tasks to a qualified professional
- Do not attempt this professional task: Inspection of pump identification wiring
- Do not attempt this professional task: Confirmation of installed pump compatibility
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Inspection of pump identification wiring
What they doA qualified gas technician accesses the pump and checks its wiring against the appliance diagram under the required electrical safety precautions.
They must show youthe connection found and any defect corrected.
In writingthe wiring point inspected and whether that correction cleared 1019.
Confirmation of installed pump compatibility
What they doA qualified gas technician compares the fitted pump identification with the type specified for that Condens 4300iW and replaces it only if it is unsuitable.
They must show youthe fitted reference and the compatible Bosch reference.
In writingthe reason for any replacement and whether 1019 returned after the work.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Save the pump identification warning
- Who:
- you, looking only at the front panel.
- How:
- photograph 1019 and find the full boiler model in the paperwork supplied by the installer.
- Result that matters:
- that this warning belongs to your Condens 4300iW.
- If confirmed:
- give the service company both details so it can identify the specified pump.
- If not confirmed:
- ask for the message to be checked against the manual for the actual model.
- Evidence to keep:
- the 1019 display and complete appliance designation.
Evidence: Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266) · Bosch Condens 4300iW, instrucciones de uso de la caldera de condensación a gas (6720891218)
Find any recent pump replacement record
- Who:
- you, using existing paperwork.
- How:
- check whether a pump was replaced and retain its recorded part number; leave the casing closed instead of looking for internal labels.
- Result that matters:
- whether 1019 first appeared following pump replacement.
- If confirmed:
- provide that part number for a professional compatibility check.
- If not confirmed:
- report that no replacement is documented; the wiring still needs investigation.
- Evidence to keep:
- the service record and first known date of warning 1019.
Evidence: Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266) · Bosch Condens 4300iW, instrucciones de uso de la caldera de condensación a gas (6720891218)
Check pump type and connections professionally
- Who:
- a qualified gas technician.
- How:
- inspect the pump wiring and compare the installed pump type with the Bosch requirement for the appliance.
- Result that matters:
- whether a connection issue or an incorrect pump type has been established.
- If confirmed:
- repair the connection or replace the incompatible pump as the findings require.
- If not confirmed:
- record the completed checks before proposing a different repair.
- Evidence to keep:
- the identified pump reference and wiring inspection result for 1019.
Internal work on this Condens 4300iW belongs to a qualified gas technician because the casing encloses electrical connections and hot components.
Evidence: Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Junkers
- Product type
- Gas boiler
Known code variants
- Bosch 1019
- Condens 4300iW 1019
- Junkers 1019
What it means
Bosch assigns 1019 to recognition of an incorrect pump type on the Condens 4300iW. The fault row calls for checking pump wiring and confirming that the heating pump fitted is the correct type for the appliance, replacing it if required. This is an identification and compatibility warning; it is not the pump-blockage code and does not by itself establish low system water content.
Warnings and stop conditions
- Criticaleditorial warning
Should a gas smell accompany 1019, stop checking the pump warning and leave without using indoor phones, doorbells or electrical switches. Avoid flames and sparks, isolate gas and ventilate only if safe, keep people out and contact the emergency services and gas supplier from outdoors.
Evidence: Bosch Condens 4300iW, instrucciones de uso de la caldera de condensación a gas (6720891218)
Symptoms and causes
Probable causes · in order
- Pump wiring needs investigationPossible
Checking the pump wiring is the first Bosch instruction for warning 1019. The connection must be investigated before an apparent identification problem is treated as proof of an incompatible replacement pump.
Evidence: Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266)
- Incorrect heating pump type fittedPossible
The second 1019 instruction is to establish that the correct type of heating pump is installed in the appliance. Bosch calls for replacement where that compatibility check shows the fitted pump is unsuitable.
Evidence: Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266)
Virtual technician
Does 1019 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Bosch Condens 4300iW GC4300iW 24 P, instrucciones de mantenimiento y de instalación (6721835266)
Bosch Termotecnia (Robert Bosch España) · 2021 · manual
- 2
Bosch Condens 4300iW, instrucciones de uso de la caldera de condensación a gas (6720891218)
Bosch Termotecnia (Robert Bosch España) · 2021 · manual
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