Bosch Dryer Error E20 — What It Means & How to Fix It

What Does This Error Mean?

E20 on a Bosch condenser or heat pump dryer means the condensate drain system has a fault. These dryers remove moisture from laundry by condensing it into water, which must then be pumped out or collected in a tray. E20 means the water is not being removed correctly — either the pump has failed or the drain path is blocked.

Affected Models

Bosch WTH84000GB
Bosch WQB145B0GB
Bosch Serie 8 Heat Pump Dryer
Bosch WTW876H0GB
Bosch condenser and heat pump dryer models with pump drain

Common Causes

Condensate drain pump failed — not pumping water out of the dryer
Drain hose kinked or blocked — water cannot exit even if the pump is working
Float switch fault — the sensor that detects water level is stuck or faulty
Drain filter clogged with lint — restricting pump flow
Drain hose incorrectly installed — installed too high so the pump cannot push water up

How to Fix It

Empty the water collection tray if your dryer has one.

Some Bosch condenser dryers collect water in a tray in the upper section rather than pumping it out. If the tray is full, the dryer stops and shows E20. Empty it and restart.
Check the drain hose at the back of the dryer (if your model uses a hose).

The hose must not be kinked or installed so that water has to travel uphill. Maximum recommended drain height is 1 metre above the dryer base.
Locate and clean the drain pump filter — usually behind a small panel at the dryer's lower front.

Lint and debris accumulate in the pump filter over time. Unscrew the cap slowly (have a towel ready for water), remove lint, rinse the filter, and reinstall.
If the above checks out, restart the dryer and run a short cotton cycle.

If E20 clears and the dryer completes the cycle without error, the issue was the filter or hose.
If E20 persists, the condensate pump has likely failed — call Bosch service.

A working pump makes a quiet hum during drainage. Silence when drainage should occur means the pump is not running.

When to Call a Professional

If cleaning the drain filter and checking the hose does not resolve E20, the condensate pump likely needs replacing. Pump replacement is a technician job as it requires partial disassembly of the dryer base. Contact Bosch service or a qualified appliance engineer.

Frequently Asked Questions

Does my Bosch dryer collect water in a tray or pump it out?

It depends on your model and how it was installed. All Bosch condenser dryers can collect water in an internal tray — it is the default mode. If you connected a drain hose to the back of the dryer, it pumps directly to the drain instead. Check whether a hose is connected at the back of the machine.