What E40 means on your Bosch dryer
Error code E40 specifically identifies which temperature sensor has failed — the drum outlet or exhaust temperature sensor. While E01 covers general NTC faults, E40 on many Bosch models points to the secondary sensor that monitors the air temperature as it leaves the drum, used for cycle termination and overheat protection.
Symptoms
- The dryer cycles don’t end at the right time — either too early or running indefinitely
- Moisture-sensing Auto Dry cycles don’t work properly
- The dryer may overheat because it can’t monitor exhaust temperature
- E40 appears during operation
Common causes
- Exhaust NTC sensor failure — the thermistor at the drum exhaust opening fails from repeated heat cycling
- Lint contamination — lint packed around the sensor insulates it and causes incorrect readings
- Connector corrosion — heat and lint dust corrode the plug connection
Troubleshooting steps you can try
- Clean the lint system thoroughly — clean the filter, the filter housing, and vacuum around the exhaust outlet inside the dryer if accessible.
- Power reset — unplug for 60 seconds.
When to call a technician
E40 requires sensor replacement, similar to E01. The exhaust sensor is typically located at the drum outlet or in the exhaust duct housing inside the dryer. A technician will test both temperature sensors in the system and replace the faulty one. Codes may vary by model generation and series.
Need help? Schedule Bosch Dryer repair with a certified technician, or contact our team for a free diagnosis consultation.
