Bosch Dishwasher E:20, a heat pump motor that tests wrong

What E:20 means

With E:20 the machine goes quiet at the point the wash pump normally starts whirring. The heat pump both circulates water through the spray arms and heats it, and the control found that the motor windings test out of range. Bosch's test is a resistance reading across two of three motor terminals, checked against the published figure: a good reading blames the power module, a bad one the pump. A disconnected or damaged cable sets off the same code.

Common causes of E:20

Pump motor winding open or shorted
Pump cable unplugged or damaged
Power module not able to run the pump

✓ One safe check you can try

1. Do not look for a home test; the diagnosis is a meter reading with the machine dead. 2. Start a program and notice whether you can hear the wash pump spin up. 3. If it is silent, stop the cycle. 4. Tell us what you heard when you book. Do not open the base.

! Why to stop there

The reading must match a published figure for that exact pump, and a wrong guess condemns the wrong part.
The heat pump is one of the costlier parts in the machine.
A heater running without water circulating can overheat, so repeated start attempts are a bad idea.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

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Other Dishwasher codes

2HBosch Dishwasher 2H: Long Cycle Warning on Older Displays 1Bosch Dishwasher Service Test Result 1: Aqua Sensor 2Bosch Dishwasher Service Test Result 2: Heating Group 4Bosch Dishwasher Service Test Result 4: Water Filling 8Bosch Dishwasher Service Test Result 8: Temperature Sensor 16Bosch Dishwasher Service Test Result 16: Spray Diverter E:30Bosch Dishwasher E:30, voltage too high and the machine shut down E:31Water in the zeolite container - Bosch Dishwasher E:31

E:20E:20 questions

Why is this one marked high priority?

The heat pump works the wash and the heater together. If it cannot run, nothing gets cleaned, and attempts to keep running the machine risk overheating the element.

Can a loose plug cause E:20?

Yes, Bosch lists a disconnected or damaged harness as a cause. That is a quicker, cheaper repair than a pump, which is why we measure first and quote second.

Is it worth replacing the heat pump on an older dishwasher?

It depends on the machine's age and the rest of its condition. We tell you plainly, and the written price lets you compare it with the cost of a new unit before you commit.