Bosch Dryer Not Draining — Pump, Hose & Tank Sensor Fix

Bosch compact ventless dryers must actively manage the water extracted from clothes. The condensate drain system consists of a sump (collection point), a small pump, tubing leading to the removable tank or a plumbed drain, and float sensors monitoring water levels. When any component fails, the dryer stops with E:08 (tank full) or E:18 (drain timeout).

Most Common Causes

1. Blocked Drain Pump Impeller (35% of cases)

Lint that passes the filters accumulates in the drain pump impeller. Over time it forms a felt-like plug that prevents impeller rotation. The pump motor hums but water does not move.

Access: Lower front service panel (clips, no screws). The pump is at the base. Place towels down, disconnect the pump, and remove the impeller cover to clean lint from around the blades.

DIY Difficulty: Easy-Moderate Parts Cost: $0 (cleaning) or $45–$80 (pump if motor burned) Professional Repair Cost: $89–$200

2. Kinked or Blocked Drain Hose (25% of cases — direct-drain)

Direct-drain installations route a small hose from pump to sink standpipe or drain. This narrow hose (typically 8–10mm ID) kinks easily when the dryer is pushed back against the wall. Also clogs with lint/mineral deposits over time.

Fix: Disconnect hose, flush with water. Check routing for kinks. Replace if internally scaled.

DIY Difficulty: Easy Parts Cost: $0–$15 Professional Repair Cost: $89–$120

3. Float Sensor Stuck (20% of cases)

The condensate tank has a float sensor that signals when full. If the float sticks in the UP position (e.g., from scale deposits), the dryer thinks the tank is always full and displays E:08 immediately at start, even with an empty tank.

Remove tank, inspect the float mechanism. It should move freely up and down. Clean any deposits with vinegar. Gently free stuck floats.

DIY Difficulty: Easy Parts Cost: $0 (cleaning) or $15–$30 (float assembly) Professional Repair Cost: $89–$150

4. Drain Pump Motor Failure (15% of cases)

Pump motor burned out from prolonged lint jamming or age. No hum from pump area, water stays in sump.

Diagnosis: During cycle, listen at lower front for pump activation. Complete silence when it should be pumping = motor dead. Test with multimeter — motor windings should read 50–200 ohms.

DIY Difficulty: Moderate Parts Cost: $45–$80 Professional Repair Cost: $150–$250

5. Sump Clogged (5% of cases)

The sump itself (below the condenser) can accumulate a lint/soap residue plug that prevents water from reaching the pump intake.

DIY Difficulty: Moderate — requires condenser removal for access Parts Cost: $0 Professional Repair Cost: $120–$180

Step-by-Step Diagnosis

1. Check error code: E:08 = tank/sensor issue. E:18 = pump/drain timeout.
2. Is tank actually full? Empty and restart. If E:08 clears, it was simply full.
3. E:08 with empty tank: Float sensor stuck. Clean float mechanism.
4. E:18: Pump not moving water. Check for pump hum. Clean impeller.
5. Direct drain: Check hose for kinks, flush for blockages.

DIY Fix vs Professional Repair

FAQ

Q: My Bosch dryer shows E:08 immediately but the tank is empty. Why?

The float sensor in the tank is stuck in the raised (full) position. Remove tank, inspect float mechanism, clean deposits. Float should move freely.

Q: Should I connect my Bosch dryer to a drain or use the tank?

Direct drain is more convenient (never empty a tank) but requires proximity to a drain point. Either works — choose based on your laundry room layout. Direct drain has slightly higher failure potential from hose kinking.

---

Bosch dryer not draining? Our technicians clean pumps and diagnose drain systems on all WTW/WGA models. Schedule a repair →