Bosch Dryer Won't Stop — Sensor, Board & Cycle Logic Diagnosis
A Bosch compact dryer that runs indefinitely (never ending the cycle automatically) is typically a moisture sensor issue — the AutoDry system never reaches its target dryness reading because the sensors are malfunctioning. In rare cases, the control board is stuck in a cycle loop.
Most Common Causes
1. Dirty/Coated Moisture Sensors (45%)
If sensors are coated with fabric softener or mineral deposits, they read inconsistently — sometimes detecting moisture that is not there, preventing the AutoDry end-point from being reached. The cycle runs indefinitely.
Fix: Clean both sensor bars with vinegar and 400-grit sandpaper. This single fix resolves nearly half of all "won't stop" complaints.
Parts Cost: $0 | Pro: $89–$120
2. Failed Moisture Sensor (20%)
Sensor itself has failed electrically — always reads "wet" regardless of actual moisture. The board never gets the signal that clothes are dry.
Diagnosis: After cleaning, if dryer still won't stop, try Timed Dry mode (fixed duration, no sensor input). If Timed Dry ends normally, the moisture sensor system has a fault.
Parts Cost: $25–$50 per sensor | Pro: $120–$200
3. Control Board Cycle Logic Fault (20%)
Board stuck in a cycle state — timer does not advance, end-of-cycle routine never triggers. May accompany other erratic behavior (display glitches, incorrect readings).
Test: Power cycle (unplug 60 seconds). If problem resolves temporarily but returns = board has intermittent logic fault.
Parts Cost: $150–$350 | Pro: $280–$500
4. Extremely Wet or Dense Load (10%)
A legitimately very wet/dense load (e.g., direct from hand-wash without spin) takes much longer than normal. The dryer IS working correctly — it just has a lot of moisture to extract. Heat pump dryers at 65C take longer for saturated items.
Confirm: Is the load actually getting drier over time? Check every 30 minutes. If progress is happening, just slow, it is working correctly on a difficult load.
Parts Cost: $0
5. Relay Stuck On — Motor Continues (5%)
Very rare: board relay that powers the motor welds shut. Motor runs continuously even when board tries to stop cycle. Dryer tumbles but heating may cycle normally.
Diagnosis: Turn program selector to Off. If drum continues spinning, relay is stuck. Unplug dryer immediately. Board replacement needed.
Parts Cost: $150–$350 | Pro: $280–$500
Do You Have the Right Tools?
Gas leak detector ($130), thermal fuse tester ($95), belt tension gauge, and vent inspection camera ($180). Our technician arrives with $15K+ in professional tools — your diagnostic is free.
Licensed & Insured · 90-Day Warranty · Same-Day Service
Step-by-Step
- Clean moisture sensors — fixes 45% of cases.
- Try Timed Dry — if it ends normally, sensor system is the issue.
- Power cycle — does it reset the problem?
- Check if load is genuinely very wet/dense.
- Turn to Off — if drum keeps spinning, relay is stuck (unplug immediately).
Same-Day Appliance Repair
Fixed or It's Free
$89 → $0 Service Call & Diagnosis — offer ends May 25
FAQ
Q: My Bosch dryer has been running for 3 hours. Should I stop it?
Check clothes — if they are getting progressively drier, the dryer is working on a difficult load. If clothes are already bone dry and the dryer still runs, the moisture sensors are not detecting dryness. Stop and clean sensors.
Q: Is a Bosch dryer that won't stop a fire risk?
Prolonged operation increases heat stress on components and lint accumulation risk. If the dryer is overheating (clothes extremely hot, cabinet hot), stop immediately. If temperature is normal but cycle is just not ending, the risk is minimal but the issue should be fixed to prevent component wear.
Bosch dryer running indefinitely? Our technicians diagnose sensors and board logic on all compact models. Schedule a repair →
