Bosch · Washing Machine
Bosch Washing Machine E20 Error Code
Unexpected heating detected in drum
What this error means
E20 (F20) means unexpected heating—the board detected the heating element energizing without a heat command, or water temperature rising when only cold fill was requested. This is a safety code that can appear after control board relay failures.
How E20 is detected
When E20 appears on a Bosch washing machine, the control board has confirmed that water did not leave the machine within the programmed drain window. On Bosch WGG254AXUC, Bosch WGB246AXUC, and similar variants, the drain pump runs for a fixed interval—often three to seven minutes on washers and dishwashers—while a pressure switch or turbidity sensor verifies the tub or sump is empty. If water remains, the cycle stops to prevent spin with a full tub or overflow on the next fill.
Most E20 calls are resolved without parts: cancel the cycle and unplug the washer immediately if the drum feels hot unexpectedly. Restricted drain paths mimic pump failure because the impeller spins against a blocked hose or filter. Document whether the pump hums audibly during the drain step; a humming pump with no water movement points to a clogged filter or kinked hose, while silence may indicate a failed pump motor or loose wiring at the harness.
After clearing blockages, run a short cycle and listen at the drain hose for steady water flow. If E20 returns on the next load with a clean filter and straight hose, measure resistance at the pump motor connector per the service manual for your model before ordering a replacement pump assembly.
Common causes
- Welded heater relay on the main control board
- Shorted heating element to ground
- NTC sensor short giving false high-temperature readings
- Residual heat from a prior cycle misread as active heating
Step-by-step fixes
- 1Cancel the cycle and unplug the washer immediately if the drum feels hot unexpectedly
- 2Leave unplugged five minutes, then restart on a cold rinse only
- 3Do not run hot programs until E20 clears on cold rinse
- 4Note whether the drum warms during a cold-only test—that confirms a stuck heater circuit
When to call a technician
Heating during an unplugged cold test or immediate E20 on cold rinse requires element and board relay diagnosis—do not continue hot cycles.
Affected models
- Bosch WGG254AXUC
- Bosch WGB246AXUC
- Bosch WAT28400UC
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use washing machines to prevent E20 from lint and food debris buildup.
- Record when E20 appears in the cycle and whether it clears after a 60-second power reset on your Bosch washing machine—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for E20; Bosch uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting E20; reversed plugs on pumps and valves cause immediate repeat faults.