How to Troubleshoot a Bosch Washing Machine That Won't Drain (E18)

E18 means the drain pump cannot evacuate water within the allowed time (typically 5 minutes). The cause is either a physical blockage, a failed pump motor, or incorrect drain hose routing. This guide walks through systematic diagnosis.

Before You Start

• Tools needed: Flathead screwdriver, pliers, shallow pan, towels, multimeter (optional), flashlight
• Parts needed: Depends on diagnosis — drain pump BSH 00145787 if pump is dead
• Time required: 20-40 minutes
• Difficulty: Beginner to Intermediate
• Safety warning: Disconnect power. Water is trapped in the tub — drain through the filter before investigating further.

Step-by-Step Instructions

Step 1: Drain Residual Water

Open the service flap (bottom-left). Use the small drain hose (if present) to slowly drain into a pan. Then unscrew the filter cap (counterclockwise) to release remaining water. This is messy — expect 1-5 liters depending on where in the cycle it stopped.

Step 2: Inspect the Drain Filter

Remove the filter cap completely. Check for and remove: coins, hair clips, pins, underwire from bras, lint balls, and small fabric items. These are the most common blockage items. If you find any, reinstall the filter, restore power, and run a drain cycle. E18 may clear immediately.

Step 3: Check the Pump Impeller

With the filter removed, shine a flashlight into the pump housing. You can see the impeller (small plastic fan). Rotate it with your finger — it should spin freely in both directions with slight magnetic resistance. If stuck, a foreign object is behind the impeller (deeper than the filter catches). If a blade is missing or cracked, the pump needs replacement.

Step 4: Check the Drain Hose

Pull the machine forward and inspect the drain hose from the pump outlet to the standpipe. Check for: kinks (especially at the standpipe entry point), the hose lifted too high (maximum height: 39 inches above floor — pump cannot push higher), or the hose pushed too far into the standpipe (max 6 inches — deeper creates a siphon seal).

Step 5: Test the Pump Motor

If the filter is clear, impeller spins freely, and hose is correct — the pump motor may be dead. Start a drain cycle and listen at the pump area. Humming = motor running (rare blockage deeper in system). Silence = motor dead. For electrical test: disconnect pump connector, measure resistance across the 2 pins: 150-250 ohms = motor coil is good. Open circuit = motor is dead, replace pump (BSH 00145787).

Step 6: Check Control Board Signal (Advanced)

If the pump motor tests good and spins freely but does not activate during drain: the control board may not be sending the activation signal. Test for 240V at the pump connector during the drain phase (CAUTION: live test). No voltage = control board relay failure.

Troubleshooting Summary

Cost Comparison: DIY vs Professional

Need Professional Help?

• Washing machine repair service
• Bosch appliance repair

FAQ

Q: E18 happens intermittently — what causes that? A: Partial blockage that allows slow draining (passes on small loads, fails on large loads). Or a pump impeller that is partially obstructed (e.g., a sock caught behind it that blocks only at certain positions).

Q: Can I run the washer on Spin to force-drain? A: Yes — if the machine allows you to select Spin Only or Drain. This activates the pump for an extended period which may clear a partial blockage.

Q: How often should I clean the drain filter? A: Every 3 months as preventive maintenance. More frequently if you wash items with loose debris (pet hair, sand, etc).

Q: The pump works but draining is very slow — why? A: Partial blockage in the drain hose, or the hose is kinked at a point you cannot see (inside the wall or behind the machine). Disconnect the hose and run water through it to verify flow.

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