Bosch E33 fault codewhat it means and how to fix it
Too much foam. Bosch tell you to reduce the detergent, and on a machine with i-DOS automatic dosing that advice needs adapting.
Before you start
What E33 means
Bosch use E33 when the machine detects more foam than it can wash and spin through safely. Foam is a real operational problem rather than a cosmetic one: it cushions the load so the balance check cannot read it, and it makes the drain pump cavitate instead of moving water. Their guidance is short and to the point — reduce the detergent. What makes this code interesting on a Bosch specifically is i-DOS, the automatic dosing system on Series 8 and some Series 6 machines. It holds a reservoir of detergent and doses each wash by load size and soiling.
When an i-DOS machine foams, adding "use less detergent" as advice is not quite enough, because the owner is not measuring anything — the machine is. What needs adjusting is the dosing calibration and the concentration setting for the particular detergent in the tank, and using a detergent thicker or more concentrated than the system expects is a common way to end up here.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Too much detergent for the load | The main cause on any machine. Bottle doses assume a full load of heavily soiled washing in hard water, which most washes are not. | Common |
| i-DOS dosing set for a different detergent | Bosch-specific. The system doses by volume, so a concentrated liquid in a tank calibrated for a standard one will consistently over-dose. | Occasional |
| Wrong detergent type | Hand-wash formulations and products meant for top loaders foam far more than a front-loader detergent. Look for a low-foam or automatic designation. | Occasional |
| Soft water area | Detergent works harder in soft water, so a standard dose foams considerably more. Affects much of Scotland, Wales and the south west. | Occasional |
What to try yourself
Let it finish if it will. The machine normally adds rinses to clear the foam itself, and interrupting means starting over.
Run a rinse and spin with no detergent to flush out what is left before the next wash.
Cut the dose to about two thirds, and to half if you are in a soft water area. Almost nobody needs a full cap for a half load.
On an i-DOS machine, check the dosing setting rather than the cap. Confirm the concentration setting matches the detergent actually in the tank, and reduce the dosing level a step if it does not.
If it keeps foaming on a reduced dose, run a hot maintenance wash with an empty drum and no detergent to clear built-up residue out of the system.
Get a qualified appliance engineer to look at your Bosch E33
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
20 minutes
Nothing. This is a dosing adjustment, and the only lasting effect should be that you buy detergent slightly less often.
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
- E79Get it checkedThe i-DOS automatic dosing pump is blocked. Only machines with i-DOS can show this, and you can switch the feature off and carry on meanwhile.Related: detergent and foam
- E18Get it checkedThe machine could not pump out in the time allowed. Bosch point at the filter and the drain hose, and warn that the water you are about to release may be scalding.Related: same brand
- E17Get it checkedProblems with the water connection: tap, kinked hose, blocked inlet filter or low pressure. Bosch’s AquaStop hose has a filter at the tap end most owners do not know about.Related: same brand
- E23Stop — call an engineerWater has been detected in the base of the machine and the AquaStop system has cut in. Bosch say to turn the tap off immediately and stop using it until it is repaired.Related: same brand
- E32Usually simple to fixAn unbalanced load, and Bosch headline it as the machine flashing "end" at the end of the programme. They state outright that this is not a fault.Related: same brand
- E06Get it checkedThe pump is blocked by something that got into it, or the outlet hose was kinked when the machine was last moved. Both are owner jobs.Related: same brand
Own a Bosch washing machine? Save it and its codes come first next time.
Related guides
Common questions about Bosch E33
Have I damaged anything?
No. E33 is the machine noticing a problem and managing it. Years of heavy foaming is not good for a pump, but a few over-generous washes have done nothing at all.
I have i-DOS, so the machine doses itself. Why is it foaming?
Because i-DOS meters by volume against a concentration setting you configure. Fill the tank with a concentrated detergent while the setting expects a standard one and it will over-dose every wash, entirely consistently. Check that setting before anything else.
How much detergent should I be using?
Less than the bottle says unless you have a full load of genuinely dirty washing in a hard water area. For an average half load in soft water, half the recommended dose is usually plenty.
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
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.