Dishwasher
E21
The E21 error code on a Siemens dishwasher indicates a problem with the circulation pump — the component that pushes water around the appliance during a wash cycle. It’s a moderately serious fault that will stop your dishwasher from completing a cycle, but it’s often fixable without a call-out.
What does this error mean?
E21 signals that the dishwasher’s control board has detected that the circulation pump is not running correctly, is drawing too much current, or has stalled entirely. The pump is responsible for spraying water through the spray arms onto your dishes — without it working, no cleaning takes place. The machine throws E21 as a protective measure to prevent the motor from burning out.
Est. repair cost
£120–£220 professional repair (pump replacement incl. labour); £40–£80 DIY pump part only if self-fitting
🔍 Likely causes
🛠️ Step-by-step fix
1. Reset the machine: Switch the dishwasher off at the wall, wait 60 seconds, then power it back on and run a short cycle. A one-off glitch can trigger E21 — a reset clears it if the pump is fine.
2. Clean the filter and sump: Remove the bottom rack and unscrew the cylindrical filter assembly (usually a quarter-turn anticlockwise). Rinse all filter parts under the tap, remove any debris from the sump cavity, then refit and test.
3. Inspect the spray arms: Pull off both spray arms (they usually unclip or unscrew). Check the holes are clear and rinse them through. Blocked arms can back-pressure the pump.
4. Check for foreign objects in the pump: With the machine unplugged, remove the filter and reach carefully into the sump with a torch. If you can see or feel a foreign object blocking the impeller, use long-nose pliers to extract it gently. Do NOT put fingers into the impeller without confirming the machine is fully unplugged.
5. Run a hot maintenance wash: If the code has cleared, add a dishwasher cleaner (e.g. Finish Machine Cleaner) and run a 65°C cycle empty. This dissolves grease build-up that can slow the pump.
6. If E21 persists after all of the above: Stop here — the pump itself is likely faulty and requires professional diagnosis. Do not attempt to open the pump housing or base panel unless you are confident working with mains-connected appliances.
📞 When to call a professional
If E21 returns after resetting, cleaning the filter, and clearing any visible blockage, you almost certainly have a failing or seized circulation pump motor. Call an appliance engineer and tell them: ‘My Siemens dishwasher is displaying error code E21, the filter is clean, and there’s no visible blockage — I suspect the circulation pump.’ This saves diagnostic time and cost. Also call immediately if you notice any burning smell or the machine trips your fuse board.
⚖️ Repair or replace?
A circulation pump replacement by an engineer typically costs £120–£220 in the UK, including parts and labour. If your Siemens dishwasher is under 7 years old and was a mid-to-high-end model (Series 4 or above), repair is usually worthwhile. If it’s over 10 years old or a budget model, a new dishwasher from £350 upwards is likely the more economical long-term choice — especially given that other age-related faults often follow a pump failure.