Dishwasher
E21
The E21 error code on a Bosch dishwasher signals a problem with the circulation pump — specifically that water isn’t being pumped around the machine properly during a wash cycle. It’s a moderately serious fault that will stop your dishwasher from cleaning effectively, but it’s not always an expensive fix.
What does this error mean?
Your Bosch dishwasher uses a circulation pump to push hot water through the spray arms during a wash. The E21 code means the control board has detected that this pump is running but not moving water at the expected flow or pressure. In plain terms, the machine knows water should be circulating but something is blocking or preventing it from doing so correctly.
Est. repair cost
£100–£180 professional pump repair; £30–£60 DIY pump part only (if confident with appliance disassembly)
🔍 Likely causes
🛠️ Step-by-step fix
Reset the dishwasher first: switch it off at the mains, wait 5 minutes, then power it back on and run a short cycle to see if the error clears.
Clean the filter: remove the cylindrical filter at the base of the dishwasher tub, rinse it under a tap, and use an old toothbrush to scrub away any grease or debris. Refit it firmly.
Check and clear the spray arms: unclip both the lower and upper spray arms, run water through each hole, and use a cocktail stick to poke out any blocked jets. Refit and spin them by hand to confirm free rotation.
Inspect the pump inlet for blockages: with the machine empty and unplugged, remove the filter housing completely and use a torch to look into the pump inlet cavity. Remove any visible debris (glass, grit, food) using long-nose pliers — never put your fingers in blind.
Run a hot maintenance wash: add a dishwasher cleaner (e.g. Finish Machine Cleaner) and run the hottest cycle available. Limescale build-up inside the pump can sometimes clear with a descaling treatment.
If none of the above resolves the fault, the circulation pump itself likely needs replacing — this requires disassembling the base of the machine and is best left to a qualified engineer unless you are confident with appliance repair.
📞 When to call a professional
If the filter is clean, the spray arms are clear, and the error persists after a reset, call a Bosch-approved or Which?-trusted appliance engineer. Tell them you have an E21 error and that you’ve already ruled out blockages — this saves diagnostic time and cost. Any repair involving removing the pump or accessing internal wiring should not be attempted as a DIY job.
⚖️ Repair or replace?
A professional circulation pump replacement on a Bosch dishwasher typically costs £100–£180 including parts and labour in the UK. If your dishwasher is under 5 years old, repair is almost always worthwhile. For machines 8 years or older, weigh the repair cost against a new mid-range Bosch dishwasher (£400–£600) — if the repair exceeds 50% of replacement value, replacing is the smarter move.