What E21 means on your Bosch dishwasher
Error code E21 indicates that the drain pump is not operating correctly. The control board has attempted to activate the drain pump but either received no feedback (the pump isn’t running) or detected that the tub hasn’t emptied within the expected timeframe. This code specifically points to the pump motor or its mechanical components, rather than a blockage further downstream.
Symptoms
- Standing water remains in the tub after the cycle completes or pauses
- The drain pump makes no sound, or makes a continuous humming without draining
- E21 appears during the drain phase of the cycle
- A grinding or clicking noise from the pump area
Common causes
- Foreign object in the pump — glass shards, bones, fruit pits, or broken dish fragments jam the impeller
- Worn pump impeller — the plastic impeller blades erode over time, reducing the pump’s ability to move water
- Failed pump motor — the motor windings burn out, especially after prolonged operation with a partially jammed impeller
- Blocked check valve — the one-way valve at the pump outlet can stick closed, preventing water from exiting
Troubleshooting steps you can try
- Clean the drain filter — remove the filter assembly at the bottom of the tub and clear all debris. This is the most common cause of drain-related issues.
- Check the drain hose — ensure it’s not kinked, pinched, or clogged. Disconnect the hose at the sink connection and check for blockages.
- Inspect the pump cover — on many Bosch models, you can access the drain pump cover by removing the filter and twisting the pump cap. Remove any foreign objects from the impeller.
- Manual drain — if the tub is full, scoop or siphon the water out before attempting any repairs.
When to call a technician
If clearing debris from the pump and filter doesn’t resolve E21, the pump motor has likely failed and needs replacement. The drain pump on Bosch dishwashers is accessible from the base of the unit. A technician will test the pump motor’s resistance (typically 150–250 ohms) and inspect the impeller for wear. Pump replacement takes 30–60 minutes. Continuing to run cycles with E21 active will leave dirty water in the tub and can lead to odor and bacterial growth. Codes may vary by model generation and series.
Need help? Schedule Bosch Dishwasher repair with a certified technician, or contact our team for a free diagnosis consultation.
