What to check yourself
Step 1. Use less detergent next time, and mean it
Most people use two to three times what a modern front loader needs. The dose on the box assumes a heavily soiled full load in hard water. Everyday washing needs about half that, and lightly soiled items less again. This one change fixes the fault permanently in most households.
Step 2. Check you are using HE detergent
A high-efficiency machine uses a fraction of the water a top loader does, and ordinary detergent foams uncontrollably in it. Look for the HE symbol on the box. Getting this wrong produces exactly this fault every single wash.
Step 3. Knock the foam down in the current load
Mix a tablespoon of fabric softener into about two cups of water and pour it into the softener compartment. It breaks the foam down chemically. Skip this if you are washing outdoor gear, sportswear or anything down-filled, since softener ruins the coating on those.
Step 4. Check your water hardness
Soft water needs noticeably less detergent than hard water, and your supplier publishes the figure for your area. People who move from a hard water area to a soft one keep dosing the old way for years and wonder why the machine foams.
Step 5. Run an empty hot cycle with no detergent
If the fault keeps appearing even on correct doses, there is old detergent built up in the drawer, the hoses and the drum. An empty cycle at the highest temperature with nothing in it clears the residue out. Wipe the drawer and the door seal afterwards.
When to call a technician
Almost never. If foam appears with no detergent at all in a machine you have already run empty and cleaned, the pressure sensor that measures the level may be misreading, and that is worth a call. Everything else here is a dosing habit.
What the repair costs
| Repair | Part only | Fitted by a technician |
|---|---|---|
| Using less detergent | - | Free |
| Pressure sensor replacement, in the rare case it is the machine | - | $150 to $350 |
A new machine of the same class runs $500 to $1,500. Once a quote passes about a third of that on an older appliance, the repair stops making sense.
Codes people confuse this with
Questions people ask
- Why is the cycle taking so much longer than usual?
- Because the machine is adding rinses to clear the foam. That is the fault being handled rather than a second problem, and the load will finish.
- Foam is coming out of the detergent drawer. Is that dangerous?
- Messy rather than dangerous. Stop the cycle, wipe it up, and run a rinse with no detergent. Then halve your normal dose from the next wash on.
- Can too much foam cause other error codes?
- Yes, and this is the part people miss. Heavy foam interferes with the pump and can bring on a drain fault such as E18. If you are seeing both, fix the dosing first and the drain fault often goes away with it.
Which machines this applies to
Applies to
All Bosch front loaders. Shown as E33 or F33, and as E:30 -20 on machines that use sub-codes. The foam symbol on the display means the same thing.
Last checked
2026-08-03