Dishwasher
E4
The E4 error code on a Bosch dishwasher signals an overfilling or overflow fault — water has risen beyond the safe level inside the machine. It’s a moderately serious fault that you should address straight away to prevent water damage to your kitchen floor or cabinetry.
What does this error mean?
Your Bosch dishwasher uses a float switch or pressure sensor to monitor water levels. When the E4 code appears, the machine has detected too much water in the tub — either because it overfilled during the inlet cycle or because water is pooling in the base from a leak. As a safety response, the dishwasher halts the programme and may activate the drain pump to clear the excess water.
Est. repair cost
£80–£150 professional repair; £10–£25 DIY door seal; £20–£50 DIY inlet valve part (if competent)
🔍 Likely causes
🛠️ Step-by-step fix
Switch off the dishwasher at the mains and leave it for 10–15 minutes. Restart and run a short cycle — if E4 clears, the fault may have been a one-off pressure spike.
Check for suds: open the door carefully (place towels down first). If you see foam, you’ve used too much or the wrong detergent. Scoop out excess water, leave the door open to let suds settle, then run a rinse-only cycle with no detergent.
Inspect the drain hose (usually at the back or under the sink connection) for kinks, blockages, or a siphon effect. Straighten any kinks and ensure the hose loops above the base of the sink before connecting — this prevents backflow.
Pull the dishwasher forward slightly and check underneath for standing water in the base tray. If there is water present, the Aquastop flood protection has triggered. Use towels or a sponge to soak it up, then let it dry completely before running again.
Inspect the door seal for visible cracks, tears, or debris stopping it from closing flush. Clean the seal with a damp cloth and press it back into its channel. A damaged seal will need replacing — door seals cost £10–£25 and are a straightforward DIY swap.
If the error returns after all the above, the inlet valve or float switch is likely faulty. These parts sit inside the machine and require partial disassembly — at this point, call an engineer rather than attempting it yourself.
📞 When to call a professional
Call a qualified appliance engineer if the E4 error persists after clearing the base tray, checking hoses, and ruling out suds or a dirty seal — especially if you can hear the inlet valve running continuously or the machine won’t stop trying to fill. Tell the engineer you have a Bosch E4 overflow fault, whether you found water in the base tray, and whether the drain pump activates during the error. Most reputable engineers can diagnose this in a single visit.
⚖️ Repair or replace?
A professional repair for an E4 fault — typically replacing the inlet valve, float switch, or pressure sensor — costs £80–£150 in the UK including parts and labour. If your Bosch dishwasher is under 7 years old and has otherwise been reliable, repair is almost always the better value. For machines over 8–10 years old, consider that a new mid-range Bosch dishwasher starts at around £400–£500, and factor in the likelihood of further age-related faults before committing to repair costs.