Dishwasher
E20
The E20 error code on a Bosch dishwasher signals a drainage fault — water isn’t leaving the machine fast enough or at all. It’s one of the most common Bosch error codes and, in most cases, you can fix it yourself in under 30 minutes.
What does this error mean?
E20 means your Bosch dishwasher’s control board has detected that water is not draining within the expected time frame. The machine monitors drain cycles and triggers E20 when it senses standing water remaining in the sump at the end of a drain sequence. It’s essentially the dishwasher telling you: something is blocking or slowing the water’s exit route.
Est. repair cost
DIY fix: £0–£20 (cleaning products, replacement filter if damaged). Professional drain pump repair: £80–£150 including parts and call-out.
🔍 Likely causes
🛠️ Step-by-step fix
Cancel the programme and switch the dishwasher off at the mains. Wait 60 seconds, then power back on and run a short rinse cycle — a one-off glitch can sometimes clear itself with a reset.
Remove and clean the filter: twist out the cylindrical filter and lift out the flat mesh filter from the tub floor. Rinse both under a hot tap, scrubbing with an old toothbrush. Refit firmly — a loose filter lets debris reach the pump.
Check the drain pump for obstructions: with the machine empty and unplugged, remove the filters and use a torch to look into the pump inlet (the circular opening beneath the filter housing). Use long-nose pliers or tweezers to remove any visible debris, glass, or grit.
Inspect the drain hose at the back of the machine: pull the dishwasher forward slightly and check the hose for kinks or tight bends. Straighten any kinks and ensure the hose rises to at least 40cm before connecting to the waste — this prevents backflow.
Check your sink waste and U-bend: run your kitchen tap and confirm water drains freely. If the sink is slow, clear it with a plunger or drain cleaner before running the dishwasher again — a sluggish sink will always cause E20.
Run a hot maintenance wash (60°C or higher) with a dishwasher cleaner tablet or a cup of white vinegar in the base. This dissolves grease in the drain hose and pump housing that physical cleaning misses.
📞 When to call a professional
If you’ve cleaned the filters, cleared the pump inlet, confirmed the drain hose is clear, and the E20 error persists, the drain pump motor has most likely failed and needs replacing — this requires partial disassembly of the machine and is best left to an engineer. Call a Bosch-approved or Which? Trusted Trader appliance engineer and tell them: ‘Bosch dishwasher showing E20 after filters and drain hose have been checked — suspected drain pump failure.’ This helps them bring the right part.
⚖️ Repair or replace?
A drain pump replacement by a UK engineer typically costs £80–£150 all-in, including parts and labour. If your dishwasher is under 7 years old, repair is almost always worth it — Bosch machines are built to last 10–15 years. If it’s over 10 years old and has had previous repairs, a new mid-range Bosch dishwasher (£400–£600) is likely the more cost-effective long-term choice.