As an expert technician, I have diagnosed the Bosch dishwasher with the error code E21 as a failure related to the Circulation Pump (also known as the Heat Pump). This error triggers when the control module detects that the pump is not rotating at the correct speed or is completely seized. This is typically caused by debris trapped in the impeller, worn-out internal bearings, or a failure in the motor’s electrical windings.
Diagnostic Report: Bosch Dishwasher E21 Error Code
1. Power Reset
Before dismantling the unit, perform a hard reset. Disconnect the dishwasher from the power outlet or turn off the circuit breaker for 10 minutes. Restore power and start a new cycle to see if the e21 code clears.
2. Inspect the Sump and Filter
Remove the bottom rack and unscrew the Filter Assembly. Check the sump area for foreign objects like broken glass, toothpicks, or fruit pits that may have bypassed the filter and reached the Circulation Pump intake.
3. Check for Impeller Blockage
Access the Circulation Pump (usually located on the right side of the base). Check if the internal impeller can spin freely. If you feel significant resistance or a “crunching” sensation, there is likely debris inside the pump housing or the bearings have collapsed.
4. Electrical Continuity Test
Using a multimeter set to the ohms (Ω) setting, test the terminals on the Circulation Pump. Bosch heat pumps are typically 3-phase BLDC motors. Measure the resistance between the three motor terminals (pins 1-2, 2-3, and 1-3).
Expected Ohmic/Resistance Values
- Motor Windings: You should receive a consistent reading between any two of the three motor terminals. The expected value is typically 10-15 Ω. If you see “OL” (Open Loop) or a value significantly higher or lower, the motor is defective.
- Heater Element (Integrated): While
E21focuses on the motor, the integrated heater terminals should read approximately 18-28 Ω.
Estimated Repair Cost
- Replacement Heat Pump Assembly: $150 – $280 USD (Genuine Bosch parts).
- Labor (if hiring a pro): $150 – $250 USD.
Warning: Always disconnect the dishwasher from the electrical power supply and shut off the water supply line before attempting any repairs or removing access panels. Failure to do so can result in electrical shock or flooding.
Repair Difficulty: DIY (Advanced)
Replacing the Circulation Pump is a complex repair. It requires pulling the dishwasher out from the cabinetry, flipping it over or removing the side panels, and potentially dropping the entire base tray to access the pump. If you are not comfortable with advanced appliance disassembly, professional service is recommended.
I am a master Appliance Repair technician with over 35 years of experience in the field. I am passionate about helping people troubleshoot their appliances and fix common problems. My website, appliancemode.com, provides a wealth of information on troubleshooting common appliance issues and deciphering error codes. This website aims to empower people to tackle appliance repairs themselves and save money on service calls.
