Dishwasher
E20
The E20 error code on a Siemens dishwasher indicates a drainage fault — the machine can’t pump water out at the end of a cycle. It’s a common issue and often fixable yourself in under 30 minutes.
What does this error mean?
Your Siemens dishwasher monitors how quickly water drains after each wash cycle. When it detects that water isn’t clearing fast enough — or at all — it throws the E20 code and stops the programme to prevent flooding. In most cases, the machine has detected standing water in the base or a blockage preventing the drain pump from doing its job.
Est. repair cost
DIY fix (filter clean, hose check): £0. Drain pump replacement: £80–£140 fitted by an engineer. Drain pump part only: £25–£55.
🔍 Likely causes
🛠️ Step-by-step fix
Reset the machine first: switch it off at the wall for 60 seconds, then restart. If E20 clears and the cycle completes, monitor for recurrence.
Clean the drain filter: remove the lower basket, unscrew the cylindrical filter at the bottom of the tub, and rinse both the mesh filter and the flat coarse filter under the tap. Refit and run a short cycle.
Check the drain hose: pull the dishwasher out slightly and trace the corrugated drain hose to the waste pipe or U-bend. Look for kinks, tight bends, or blockages. The hose outlet should sit no higher than 60cm from the floor unless a standpipe is used.
Clear the sink waste: remove and clean the U-bend under your kitchen sink. A blocked sink drain is a surprisingly frequent hidden cause of dishwasher E20 faults.
Inspect the drain pump: with the machine unplugged and water bailed out, remove the filter assembly and use a torch to look into the pump inlet at the base. Carefully remove any visible debris (glass, toothpick, bone fragment) using long-nose pliers — never put your fingers in blind.
Check the base tray for water: if all the above checks out but E20 persists, tilt the machine slightly forward to drain any water trapped in the base tray, which may have triggered the float switch. If you find water there, there is a small internal leak that needs a professional to diagnose.
📞 When to call a professional
Call a qualified appliance engineer if the drain pump runs but water won’t clear, if you find water in the base tray (indicating an internal leak), or if E20 returns within a few cycles after cleaning the filter. Tell the engineer: ‘My Siemens dishwasher is showing E20 — I’ve cleaned the filter and checked the drain hose, but the fault persists.’ This saves diagnostic time and money.
⚖️ Repair or replace?
A drain pump replacement by an engineer typically costs £80–£140 including parts and labour in the UK. If your Siemens dishwasher is under 7 years old and was a mid-range or premium model (originally £400+), repair is almost always worth it. If it’s over 10 years old or was a budget model, a new dishwasher from around £350 is likely the smarter long-term spend.