- Appliances
- Refrigerators
alarm
Bosch alarm on a fridge freezer: freezer temperature too high
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
On Bosch KGN fridge freezers, a warning tone with the freezer set temperature and alarm off flashing means the freezer has become too warm. Press alarm off, close the freezer door properly, clear the vents and check whether any food has thawed.
Safety first
Stop and check this first
- Never block the ventilation openings: the manual warns that a leak in the refrigeration circuit could then form a flammable gas and air mixture. Do not pierce or scrape the inner walls.
- Bosch warns that bacteria can multiply while food thaws: do not refreeze defrosted food unless it has been cooked first.
Safe checks you can perform
- Work out which warning the panel shows
- Freezer door shut all the way
- External vents and clearances
- Check the frozen food
- Use Super freezing before a big shop
Leave these tasks to a qualified professional
- Do not attempt this professional task: Appliance self-test and temperature reading
- Do not attempt this professional task: NoFrost check if the set temperature is not reached
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.
Appliance self-test and temperature reading
What they doA Bosch customer service engineer runs the appliance self-test, where 2 audible signals mean the sensors are fine and 5 signals with LEDs at different brightness flag a fault, and measures the real freezer temperature.
They must show youthe self-test result and the temperature measured in the freezer.
In writingthe warning seen, the self-test outcome, the measured temperatures and any part replaced.
NoFrost check if the set temperature is not reached
What they doWhen the freezer cannot reach its set temperature after a long door opening, Bosch says to switch off, disconnect from the mains and call customer service, as the noFrost evaporator may be heavily iced up.
They must show youthe state of the evaporator and the fan running after the work.
In writingwhat was found at the evaporator, the defrost or repair done and the temperature reached afterwards.
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.
Work out which warning the panel shows
- Who:
- you, just by watching the Bosch control panel.
- How:
- watch the panel. A warning tone with the freezer set temperature and alarm off flashing is the temperature alarm. A tone with alarm off lit and a door open is the door alarm. If all temperature displays and alarm off light up together, Bosch says a sensor is defective.
- Result that matters:
- knowing which of the warnings you have before doing anything else.
- If it is the temperature alarm:
- press alarm off to silence it and carry on with these checks.
- If all displays and alarm off stay lit:
- call Bosch customer service.
- Evidence to keep:
- short video of the panel while the alarm sounds.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Freezer door shut all the way
- Who:
- you.
- How:
- make sure the freezer door closes fully and that no drawer, tub or bag holds it slightly open. Bosch names a freezer door left open as one of the listed causes of this alarm, so this is the first thing to rule out.
- Result that matters:
- a door that shuts completely with nothing in the way.
- If a drawer or pack held the door open:
- rearrange the load and watch whether the temperature recovers.
- If the door was shutting fine:
- look at ventilation and recent loading.
- Evidence to keep:
- photo of the freezer load with the door open.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
External vents and clearances
- Who:
- you.
- How:
- check that the external ventilation openings are not covered by cloths, boxes or units. The manual says never to cover them, to leave a small gap between the side wall and the appliance and to keep 300 mm away from oil or solid-fuel cookers.
- Result that matters:
- clear vents and the appliance away from heat sources.
- If something was covering the vents:
- remove it and check the temperature a few hours later.
- If the vents were clear:
- think about whether you added a lot of fresh food recently.
- Evidence to keep:
- photo of the front and side of the appliance in its space.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Check the frozen food
- Who:
- you.
- How:
- open the freezer only briefly and feel whether the food is still frozen hard. The Bosch manual says not to refreeze food that has defrosted or started to defrost unless it has been cooked first, and not to keep such items for the maximum storage period.
- Result that matters:
- knowing what is still frozen and what must be cooked or thrown away.
- If everything is still frozen:
- close the door and let the appliance recover.
- If some items are soft:
- cook them before refreezing or discard them.
- Evidence to keep:
- a note of which items you found thawed.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Use Super freezing before a big shop
- Who:
- you.
- How:
- look up the maximum freezing capacity on the rating plate and stay below it. Bosch says to switch on Super freezing before placing large quantities of fresh food in the freezer.
- Result that matters:
- fresh food loads that stay within the freezing capacity.
- If the alarm came after a big shop:
- let the freezer recover and spread future loads.
- If you had not added food:
- if the alarm keeps returning without reason, book a repair.
- Evidence to keep:
- photo of the rating plate showing the freezing capacity.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
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
- Appliances
- Brand
- Bosch
- Product type
- Refrigerators
Known code variants
- alarm
- alarm off
- alarma
- alarma de temperatura frigorífico Bosch
- alarma de temperatura frigorífico Siemens
- alarma puerta abierta Whirlpool
- alarma temperatura frigorifico Whirlpool
- Bosch combi alarma congelador
- Bosch freezer temperature alarm
- Bosch fridge beeping alarm
- Bosch fridge freezer alarm
- Bosch frigorífico alarm
- Bosch KGN alarm off flashing
- Bosch KGN alarm parpadea
- congelador Bosch pita alarm
- congelador Siemens pita alarm
- Door Ajar Alarm Whirlpool refrigerator
- Door Alarm Light Whirlpool
- luz de alarma parpadeando Whirlpool
- Over Temperature alarm Whirlpool
- Siemens freezer temperature alarm
- Siemens fridge beeping alarm
- Siemens fridge freezer alarm
- Siemens frigorífico alarm
- Siemens iQ300 alarma congelador
- Siemens iQ300 freezer alarm
- Siemens KG39N alarm flashing
- Siemens KG39N alarm parpadea
- Stop Alarm Whirlpool
- temperature alarm
- Temperature Alarm Whirlpool
What it means
The Bosch KGN.. Information for Use for the KGN392LDFG fridge freezer (UK, 2026) says the temperature alarm switches on when the freezer becomes too warm: a warning tone sounds and the freezer set temperature and alarm off flash. It lists switching on, putting in large quantities of fresh food, a freezer door left open and covered external vents. If every temperature display and alarm off light up together, the manual points to a defective sensor. Other models may vary, and the alarm alone never proves that a part has failed.
Warnings and stop conditions
- Mediumeditorial warning
Never block the ventilation openings: the manual warns that a leak in the refrigeration circuit could then form a flammable gas and air mixture. Do not pierce or scrape the inner walls.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
- Highsource verified
Bosch warns that bacteria can multiply while food thaws: do not refreeze defrosted food unless it has been cooked first.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Symptoms and causes
Probable causes · in order
- Freezer door open for too longCommon
The manual names a freezer door left open for a long time as a trigger; a pack that stops the door from shutting does the same.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
- Large amount of fresh food addedCommon
Loading more fresh food than the freezing capacity shown on the rating plate can set the alarm off.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
- External ventilation openings coveredPossible
Bosch lists covered external ventilation openings as a cause and asks you to remove whatever blocks them.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
- Appliance has just been switched onPossible
A freshly switched-on appliance needs several hours to reach the set temperature, and the alarm can sound in the meantime.
Evidence: Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Virtual technician
Does alarm 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 Manual de usuario frigorífico combi KGN.. (KGN39AIBT)
Bosch · 2026 · manual
- 2
Bosch Information for Use fridge-freezer KGN.. (KGN392LDFG)
Bosch · 2026 · manual
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