The short answer
F33 on this washing machine means detergent foam has been detected, from too much detergent or an old detergent, and it is more likely on lightly soiled loads — that is what the manufacturer published for it, and no more. The machine is usable; it is reporting the detergent rather than a fault, so the change needed is in the dose. One of the checks below is an owner check, and the rest of the work is behind a panel.
Error codes
Reference| Code | Meaning |
|---|---|
| F33 | Detergent foam has been detected. Too much detergent or an old detergent was used. This may cause excessive foaming from the detergent compartment. This may happen when washing lightly soiled items. |
What the machine does alongside the code
- Extra rinses added and a spin that will not reach speed — The machine deals with foam before it reports it, which is why the cycle runs long.
- The cycle runs long, with extra rinses — The control adds rinses to get rid of foam before it reports anything.
What triggers F33, most likely first
- Too much detergent for the load — It goes first because the published description names it: dose instructions assume a full, soiled load in hard water, and the same dose in a small or lightly soiled load foams heavily.
- A lightly soiled load — It ranks here because it surprises people: soil consumes detergent, so a clean load with a normal dose has nothing to absorb the product and foams instead.
- Very soft water — Last, and the one people never suspect: soft water needs markedly less product, and a dose that suits a hard-water area foams heavily in a soft one.
Check in this order, and why
- Compare the dose you used against the product instructions for that load — Most overdosing is by a factor of two or more, and this is where it shows up.
- Check the product is intended for this appliance — A high-foaming product is a cause no amount of dose adjustment resolves.
- Body: Look at the product before the machine: type, dose, load size and water hardness explain almost all of these codes between them.
The reset, then the owner-safe checks
- Run a maintenance or hot cycle with the drum empty — This clears accumulated residue that is adding to every dose you measure.
About 90 min
- Run a rinse and spin with no product, then halve the dose for the next few loads — Repeat the rinse if foam is still visible through the glass at the end.
About 40 min
- Clean the dispenser drawer and its housing — Residue there dissolves into the next cycle on top of whatever you have measured out.
Tools: soft brush, warm waterAbout 15 min
- STOP HERE if the code appears with no foam and a correct dose — That is a sensing fault rather than a foam one, and it needs the appliance open.
Before anything is opened
Safety
Unplug the machine or switch off its breaker before any panel comes off — a capacitor can hold a charge after the power is off. Close the supply tap before touching a hose, expect standing water when a filter comes out, and never work round the door interlock.
When this is a service call rather than a reset
Call if foam is escaping from the cabinet rather than staying in the drum, or if the code persists after an empty maintenance cycle and a reduced dose.
Neighbouring codes on Bosch washing machines
What this page does not cover
This reading applies to the Bosch washing machine line as a whole, not to one family or model. It does not cover what differs between model lines — wiring colours, connector positions, part numbers and service-mode sequences — which are in your own model manual and which a technician matches to the rating plate rather than to this code. Where a family- or model-specific page for this code exists, it is linked from the code index below and it is the more specific answer.
Links: - [Bosch washing machine error codes](/blog/bosch-washer-error-codes)
Where to go next
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
