Bosch · Dryer
Bosch Dryer E01 Error Code
Lint filter airflow sensor blocked
What this error means
E01 is Bosch's early airflow warning—the lint filter sensor detects restricted exhaust before critical overheating. Heat-pump models like the WTG86400 series will continue running but drying times stretch and the display holds E01 until airflow improves.
How E01 is detected
When E01 appears on a Bosch dryer, the control board has confirmed that water did not leave the machine within the programmed drain window. On Bosch WTG86401UC, Bosch WTG865H4UC, 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 E01 calls are resolved without parts: pull the lint screen and peel off all lint—rinse under warm water on washable filters. 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 E01 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
- Lint screen packed after several loads without cleaning
- Secondary mesh filter on heat-pump models caked with fine lint
- Filter installed upside down or not fully seated in the track
- Moisture sensor strips coated with dryer-sheet residue near the filter housing
Step-by-step fixes
- 1Pull the lint screen and peel off all lint—rinse under warm water on washable filters
- 2Vacuum the filter channel inside the door opening
- 3On heat-pump dryers, remove and rinse the condenser cartridge per the maintenance flap guide
- 4Run one timed cycle and confirm E01 clears in the first five minutes
When to call a technician
If E01 returns immediately after a fully cleaned filter and condenser, the airflow sensor or blower housing needs service.
Affected models
- Bosch WTG86401UC
- Bosch WTG865H4UC
- Bosch WQB245AXUC
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use dryers to prevent E01 from lint and food debris buildup.
- Record when E01 appears in the cycle and whether it clears after a 60-second power reset on your Bosch dryer—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for E01; Bosch uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting E01; reversed plugs on pumps and valves cause immediate repeat faults.