Bosch Demo modewhat it means
BSH’s own words are that in demo mode the appliance runs cold. It lights up, appears to work, and generates nothing at all.
Before you start
What this means
BSH publish two entries about this and both are worth having. The first says demo mode is activated, that in demo mode the appliance runs cold, and that you deactivate it as described in the instruction manual. The second says a button combination for test mode was inadvertently activated and that pressing the On button deactivates it. A third entry, filed under the display symptom "small squares", gives the reason as a button combination for demo mode being inadvertently activated and a longer release: switch the appliance off, touch the Info button for three seconds and scroll until the lock has been selected, then touch the clock button for three seconds. What all three describe is a shop-floor mode. Retailers need an appliance that lights up, accepts button presses, counts down and looks alive on a display stand where nothing is plugged into a proper supply and nobody wants a hot microwave in a showroom.
So the manufacturer builds a state where every part of the appliance works except the part that generates power. The problem is that it does not always get switched off before the appliance is delivered, and it can be triggered by a button combination afterwards. What an owner then experiences is the most confusing failure in this category. The microwave is not broken in any visible way. The light comes on, the turntable turns, the fan runs, the timer counts down and the finish tone sounds. The food is cold. That looks exactly like a magnetron fault, which is a two-hundred-pound repair, and it is a setting. BSH’s phrase for it — "runs cold" — is the most useful three words in their microwave dataset. Their manuals supply what the database defers to.
On the Serie 4 built-in BFL523 and BFL524 family, Siemens’ iQ500 BF525LM family and the freestanding FFL023 family, demo mode is basic setting 2: with the appliance switched off you press and hold start and stop together for a few seconds, turn the selector to setting 2, press start, set it to off and press start again to accept, then stop to leave. While demo mode is on those displays show an M, and the freestanding manual spells out what the state is: the buttons and display work but "no power arises for the microwave". The Serie 8 BFL634 family with the TFT display hides the setting after start-up — its manual says demo mode is only displayed during the first three minutes after the appliance has been reset or used for the first time, so the exit is to switch the appliance off at the fuse box, switch it back on, and deactivate demo mode in the basic settings within three minutes. So a microwave that appears to work perfectly and heats nothing is worth checking against this page before anyone calls anybody.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Delivered from a retail display without being reset | An ex-display or clearance appliance can arrive in the mode it was demonstrated in, working from day one and heating nothing. | Common |
| A button combination pressed inadvertently | BSH name this cause themselves in two separate entries, and it is the reason it can appear years into ownership. | Common |
| Triggered during cleaning | Wiping the fascia presses several keys at once for several seconds, which is the shape of most mode combinations. | Occasional |
| Service test mode rather than demo mode | BSH document these as two states with two different releases, and the display symptom does not always distinguish them. | Occasional |
What to try yourself
Confirm the symptom first. Put a mug of water in, run it for a minute on full power, and check whether the water is warmer. A microwave that runs and does not heat is the case this page is about.
Look for anything unusual on the display — an M, a word like Demo, or rows of small squares. Bosch’s Serie 4, iQ500 and freestanding manuals say an M on the display means demo mode; BSH treat small squares as a separate published symptom of the same underlying state.
On a Serie 4 built-in, a Siemens iQ500 built-in or a Bosch freestanding model, switch the appliance off, press and hold start and stop together for a few seconds until the first basic setting shows, turn the rotary selector to setting 2, press start, turn the selector to off, press start to accept and stop to leave. That is Bosch’s printed route and the whole of it.
On a Serie 8 model with the TFT display, the setting only appears in the first three minutes after power is restored: switch the appliance off at its fuse, switch it back on, and go straight into the basic settings to turn demo mode off before the three minutes are up.
For the small-squares display, follow BSH’s database sequence — switch the appliance off, touch the Info button for three seconds, scroll until the lock has been selected, then touch the clock button for three seconds. For the test-mode version their release is simply to press the On button.
Test with water again. If it heats, the appliance was never faulty, and you have avoided a repair bill for a part that was working the whole time.
Get a qualified appliance engineer to look at your Bosch microwave
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What it costs to fix
Typical repair cost
£0
Time on site
10 minutes
Nothing at all. This is the cheapest fault on the site and the most expensive one to misdiagnose, because the symptom is identical to a magnetron failure at two hundred pounds.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Bosch fault codes
- Key symbolUsually simple to fixNot a fault. BSH publish this as the childproof lock, released by holding the key-symbol button until the symbol goes out — about four seconds in Bosch’s manuals; freestanding models show SAFE.Related: settings and modes
- E-3Get it checkedA fault in the automatic door opening system, in Bosch’s own words. Their UK built-in microwave manual says switch off, wait ten minutes, switch on; their troubleshooting database files the code under ovens.Related: same brand
- E-11Get it checkedThe one microwave code Bosch name in their North American manual. The touch keys are not working properly, and condensation on the keypad is the cause they give.Related: same brand
- ExxGet it checkedBosch’s own placeholder for every microwave code they have not defined. Their instruction is to note the number, isolate the appliance and call a technician.Related: same brand
- E0532Usually simple to fixA button pressed too long or jammed. BSH publish one answer under three labels and it is the only microwave entry where they give the owner a real fix.Related: same brand
- Temperature too highGet it checkedBSH’s database publishes this and "000" flashing against one answer: the appliance has not cooled down completely, wait. Bosch’s own UK manuals read three flashing zeros differently — a power cut, set the clock.Related: same brand
Own a Bosch microwave? Save it and its codes come first next time.
Related guides
Common questions
How can it run and not heat?
Because the light, the turntable, the fan and the timer are all driven separately from the power generation. Demo mode leaves everything visible working and disables only the part you cannot see. BSH describe it as running cold, which is exactly what it does.
Would this happen on a brand-new appliance?
It is one of the likeliest explanations for a new microwave that appears to work and heats nothing, particularly an ex-display or clearance one. It is worth ruling out before you start a warranty claim, because the answer is a keypress.
How do I tell this from a failed magnetron?
You often cannot from the outside, which is the whole problem — both present as a perfectly behaved microwave producing cold food. That is the argument for trying the releases here first: they cost nothing, and the alternative diagnosis costs a visit.
Is demo mode the same as test mode?
BSH publish them as two states with two different exits. Demo mode points you at the instruction manual, which on the current ranges means basic setting 2 reached by holding start and stop; service test mode is released by pressing On. If one does not work, try the other before concluding either is wrong.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer support portal
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.