Soak the filters flat in hot water with a non-caustic degreaser rather than putting aluminium mesh through a dishwasher. If a Siemens-badged replacement is hard to find, measure the equivalent Bosch or Neff part, because BSH hoods frequently share components.
Siemens hoods are BSH appliances alongside Bosch and Neff, and the practical benefit of that shows up when you need a part.
Filters lose their labels, and that is when it matters
Hood filters sit in a warm, greasy environment where any sticker gives up within a few years, and replacements are listed by dimension rather than by badge.
Because Siemens, Bosch and Neff hoods frequently share filter sizes, mounting arrangements and motor assemblies, a Siemens part that appears unobtainable for an older hood has a reasonable chance of being in stock under a sibling name. Measure the filter and search the dimension rather than the brand.
It also means a mixed BSH kitchen, which is common where appliances were bought at different times, takes one approach across all of it. See how to clean a Bosch rangehood and how to clean a Neff rangehood.
Ducted or recirculating
Ducted hoods carry metal grease filters only. Recirculating hoods, common in apartments where ducting outside is impossible, also carry a charcoal filter behind them for odour, replaced every six to twelve months and never washed.
If nobody has ever replaced yours, the hood is doing nothing about smell and has not been for some time.
The rest of the method
Filters soaked flat, then the impeller housing behind them with the power isolated first. Our rangehood cleaning guide covers it in full, including why aluminium mesh must never go in a dishwasher.
Where the smell actually is
If a Siemens hood smells after the filters have been soaked, the deposit causing it is behind them.
Everything the filters miss is thrown against the fan housing by the impeller and bakes into a hard brown lacquer that warms every time the hood runs. It is also what unbalances the fan, so a hood that was quiet develops a hum and then a rattle, and what reduces extraction, because a loaded impeller simply moves less air.
Isolate the power at the wall or the circuit breaker before anything goes near it, because an impeller starting with a hand in the housing causes serious injury and hoods are frequently wired to a switch that is not obvious.
What actually goes wrong
A parts search under one badge when the component is listed under another.
An original charcoal filter in a recirculating install.
Grey mesh from a dishwasher cycle.
Should you do it yourself?
Do it yourself for the filters every couple of months.
Get someone in for the impeller housing, or alongside the Siemens oven in one visit.