What this code means
On Bosch washing machines, the E20 (or F20) error code indicates the control system has detected unexpected heating during a cycle. This fault is related to the heating circuit, not drainage or pump issues. Bosch’s official guidance is to turn the washer off briefly and then back on to reset the control. If the code reappears after the reset, the machine has a persistent heating-control problem that requires service.
Many third-party sources incorrectly describe E20 as a drain or pump code, but Bosch’s published washer support page clearly identifies E20/F20 as a heating fault. The error means the washer registered a temperature rise it did not command, pointing to a stuck relay, faulty sensor, shorted heater element, or control-board output failure in the heating circuit.
Before You Replace Anything
Homeowners sometimes replace the drain pump or clean filters after reading third-party advice that calls E20 a drainage code. Check the Bosch model support page to confirm the code meaning before ordering parts.
Common Causes
- Faulty heating element A shorted or stuck-on heater element can cause uncontrolled heating that triggers the fault.
- Temperature sensor failure An out-of-range or open thermistor prevents the control board from reading water temperature accurately, and the board may interpret erratic readings as unexpected heating.
- Control board relay stuck closed A stuck relay or triac on the main board can keep power flowing to the heater even when the cycle does not call for heat.
- Damaged wiring or connectors Heat-damaged or corroded connectors in the heating circuit can create intermittent shorts or false signals.
- Software glitch or transient fault A one-time electrical noise event can set the code without any hardware damage, which is why Bosch recommends a reset first.
Step-by-Step Fix
- Turn off the washer at the power button or unplug it from the wall outlet, and wait at least 30 seconds to allow the control board to reset.
- Restore power and select a short rinse or drain cycle to see if the E20 code reappears on the display.
- If the code returns, unplug the machine and pull it away from the wall so you can access the rear service panel.
- Remove the rear or top panel (fastener locations vary by model) and locate the heating element at the bottom of the tub and the temperature sensor or thermistor nearby.
- Disconnect the heater and sensor connectors from the wiring harness, inspect the terminals for burn marks or corrosion, and use a multimeter to measure resistance across the heater element pins and the sensor pins (consult your model’s service manual for expected values, as Bosch does not publish these publicly).
- Replace the heating element if it shows a short to ground or infinite resistance, or replace the temperature sensor if it reads open or far outside the typical range for room temperature.
- Reassemble the washer, run a test cycle with hot water selected, and verify that the temperature rises normally without triggering the E20 code again.
Parts Often Needed
| Part | Notes |
|---|---|
| Bosch washer heating element | Amazon | Match the part number to your model prefix; heater wattage and mounting flange vary by series. |
| Bosch washer temperature sensor / thermistor | Amazon | Often a two-wire NTC sensor mounted near the sump or in the heater housing. |
| Bosch washer main control board | Amazon | Required only if testing confirms the relay or triac output is stuck closed; verify the board part number before ordering. |
When to Call a Pro
Call a qualified appliance technician if the E20 code persists after a reset, or if you are not comfortable working with 120-volt or 240-volt circuits inside the washer. Testing the heating element, thermistor, and control board outputs requires a multimeter and knowledge of safe disassembly. A technician will isolate the fault in the heating circuit, verify component resistances against the service manual, and replace the defective part. Do not continue to run the washer if you smell burning plastic or if the tub feels excessively hot, because a stuck heater can damage the drum seal or create a fire hazard. Professional diagnosis typically costs between $100 and $150, and total repair costs range from $150 to $350 depending on whether the heater element, sensor, or control board needs replacement.