Try every programme and note which produce heat
If conventional baking is cold but the grill glows, the lower element is the suspect. If the fan programme is cold but conventional works, the ring element behind the back panel is. If nothing heats at all on any programme, the problem is upstream of the elements, in the supply or the control. Ten minutes of trying settles which of the three you have.
What you find
- The grill works but the oven never warms for baking — One element out of several, which points at the lower heater.
- Fan programmes stay cold while conventional heating works — The ring element around the blower, which sits behind the rear panel.
- Nothing heats on any programme although the display works — Upstream of the elements: supply, control or a thermal cut-out.
- The oven warms but never reaches the set temperature — Partial heating rather than none, which usually means one of several elements is out.
- A visible blister, split or bright spot on an element — Direct evidence, and it is visible with the oven cold and the light on.
- NEAR MISS: a fan running with no heat during a cooling phase — Normal behaviour after use rather than a fault.
Ranked for a multi-element oven
- A failed heating element — First. Elements run hot for years and eventually open, and because each programme uses a different combination, the failure shows as a missing function rather than a dead oven.
- A thermal cut-out that has operated — Second. A restricted installation or a self-clean cycle can trip a protective device, which leaves the whole cavity cold with the display alive.
- Supply trouble on a split circuit — Third. An oven can lose part of its supply and keep the electronics working, which is why the display can look perfectly healthy.
- The control or the temperature sensor — Last. Both exist, and both are far less common than an element that has simply come to the end of its life.
Map the programmes, then look
- Run each programme briefly and record which give heat — It identifies the failed element without any tools and it is the core of the diagnosis.
- Look at each visible element with the oven cold and the light on — The top cause is often visible as a blister or a bright scar.
- Check the breaker is fully on, not merely not tripped — It addresses the third cause and takes a moment.
- Consider the cut-out and the control only when no programme heats — Those are the upstream causes and they belong after the element map.
Owner steps
- Set each programme in turn for a few minutes and note whether heat appears — This is the whole diagnosis. Write the results down rather than trusting memory.
Tools: notepadAbout 30 min
- With the oven cold, look closely at the upper and lower elements — A failed element often shows a blister, a split or a bright discoloured section.
Tools: flashlightAbout 10 min
- Check the breaker for the oven is firmly on and reset it once — An oven that has lost part of a split supply still lights its display, which misleads everyone.
About 10 min
- Check nothing blocks the ventilation around a built-in housing — Restricted airflow is what causes a protective cut-out to operate in the first place.
Tools: flashlightAbout 10 min
- STOP before the rear panel or any element connection is disturbed — Mains voltage and a heating circuit sit behind them, and that is where owner work ends.
Before any panel comes off
Safety
Unplug the appliance or switch off its breaker before removing any cover, and let the cavity cool completely first. Never run a self-clean cycle to test an oven that has already failed to heat. If an element is visibly damaged, stop using the oven: a split element can arc. Stop immediately and call if you see sparking or smell burning.
When to call
Call once the programme map shows a missing function, because replacing an element means working on a mains connection inside a hot cavity. Call immediately for sparking, a burning smell or a breaker that trips when the oven calls for heat. Bring the map of which programmes work: it usually tells the technician which part to bring.
Nearest pages of this class
Scope
Written for the Bosch oven class rather than one model line. Element arrangements, cut-out positions and programme names differ by family, and those details belong on the page for your specific appliance.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
