Common causes of humming from a Bosch dishwasher

Have you started your Bosch dishwasher, only to hear an unexpected humming noise that wasn’t there before? It’s a common problem that can leave you wondering what’s going on inside your appliance. The good news is that many causes of humming noises are straightforward to fix on your own. Let’s dive into the common reasons your Bosch dishwasher might be humming and how you can resolve them.

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Please note: The information provided here may not align perfectly with your specific appliance model. While we strive to offer helpful tips for a wide range of DIY appliance repairs, different models and setups may require unique troubleshooting steps, error codes, or part replacements. For the most accurate guidance, we recommend consulting the user manual for your appliance or contacting us with any questions.

Common causes of humming noises 

Understanding why your dishwasher is humming is the first step toward fixing the problem. Here are some common causes:

• Improper loading: Sometimes, the humming noise may simply be due to items in the dishwasher vibrating against each other.
• Spray arm: When debris or food particles get stuck in the spray arm or impeller, they can cause a humming sound as the water isn’t flowing properly.
• Filter: A clogged filter can restrict water flow, causing the dishwasher to make a humming noise as it struggles to pump water.
• Pump impeller:  The pump impeller circulates water throughout the dishwasher. If it becomes clogged or blocked by debris, it can cause a humming noise.
• Water inlet valve:  The water inlet valve controls the flow of water into the dishwasher. A malfunctioning valve can cause a humming sound when it fails to open or close properly.
• Drain pump:  A build-up of debris or food particles in the drain pump can cause it to make a humming sound while trying to drain.
• Circulation pump motor:  The circulation pump motor powers the impeller that moves water through the dishwasher. A humming noise can indicate that the motor is failing.

Safety precautions

Safety comes first when working on any appliance. Here are some practical tips to help keep you safe:

• Always turn off the power by unplugging the appliance or switching off the circuit breaker before starting. This protects you from the risk of electric shock.
• Wear insulated gloves to protect your hands from sharp edges, pinching hazards, or debris.
• Take your time and work at a steady pace to avoid accidents or injuries.
• Make sure your workspace is well-lit so you can clearly see and access the parts you’re working on.
• Keep your area organized and free of clutter, and ensure children and pets are kept away from the workspace.
• Never handle internal parts with wet hands. Make sure both your hands and the work area are completely dry.
• Check your appliance’s user manual for specific instructions or safety guidelines related to your repair.
• Handle parts gently to prevent damaging the appliance or injuring yourself by using too much force.
• Wear safety glasses if you’re dealing with chemicals, dust, or large debris to protect your eyes.
• If the appliance was recently used, give it time to cool down before working on any heated components.
• Take photos or notes of wiring connections before disconnecting anything. This makes reassembly much easier.
• Avoid touching exposed wires or terminals. If you need to handle wires, use non-conductive tools or wear insulated gloves to reduce the risk of electrical shock.

Read more: surprising things that can and can’t go in the dishwasher

Troubleshooting steps

Improper loading

1. Inspect the load: Open the dishwasher and check if any items are touching the spray arms or interfering with other dishes. Items that are too close together or improperly arranged can vibrate against each other during the wash cycle, causing a humming sound.
2. Rearrange the load: Move the items around to ensure there is enough space for the spray arms to rotate freely. Ensure large items, like pots or pans, are placed properly and smaller items are securely positioned.
3. Test it out: Run a cycle with a well-arranged load and check if the humming noise persists. If it stops, improper loading was the issue.

Spray arm

1. Inspect the spray arms: Open the dishwasher and look for any visible debris or clogs in the spray arm holes. Use a flashlight if necessary.
2. Remove debris: If you find debris, use a small brush or toothpick to clear the holes. You can also rinse the spray arms under water to ensure water flows through each hole.
3. Check spray arm movement: Spin the spray arm manually to see if it moves freely. If it’s stuck or obstructed, remove it and clean the area around it.
4. Test it out: Run the dishwasher again to see if the humming sound is gone.

Filter

1. Locate the filter: The filter is typically located at the bottom of the dishwasher. Open the dishwasher and pull out the bottom rack to access it.
2. Remove the filter: Take the filter out of the dishwasher. Check for any debris or food particles that may be clogging it.
3. Clean the filter: Rinse the filter under warm water and use a soft brush to scrub away any stubborn debris.
4. Reinstall the filter: Once clean, place the filter back into its slot.
5. Test it out: Run a cycle to see if the humming noise stops. A clogged filter can reduce water flow, causing the humming.

Pump impeller

1. Access the pump impeller: Depending on your dishwasher model, you may need to remove the bottom rack and possibly the filter to access the pump impeller.
2. Inspect the impeller: Check if any debris is blocking the impeller. Use a flashlight to see if something is lodged in the pump area.
3. Clear the blockage: If you find debris, carefully remove it. A soft brush or small tool can help you dislodge the material. Be gentle to avoid damaging the impeller.
4. Check the impeller’s movement: Spin the impeller by hand to make sure it rotates smoothly.
5. Test it out: Run a cycle and listen for any humming. If the impeller was blocked, clearing it should eliminate the noise.

Water inlet valve

1. Locate the valve: The water inlet valve is usually located at the bottom of the dishwasher, near the front. You may need to remove the kick plate or bottom panel to access it.
2. Inspect the valve: Check the valve for any visible damage, such as cracks or corrosion. Also, check for any debris or blockages in the valve’s opening.
3. Test the valve: Using a multimeter, check the water inlet valve for continuity. If there’s no continuity, the valve may need to be replaced.
4. Test it out: If the valve was faulty and has been replaced, run a cycle to ensure the humming noise is gone.

Drain pump

1. Locate the drain pump: The drain pump is typically located at the bottom of the dishwasher near the motor. You may need to remove the bottom rack and filter to access it.
2. Check for debris: Inspect the drain pump area for any debris or food particles that may be blocking the pump. Use a flashlight to get a better view.
3. Clean the pump area: If you find any blockage, carefully remove it. A small brush or tweezers may be helpful for clearing debris.
4. Test it out: After cleaning, run a cycle to check if the humming noise has stopped. If the pump was blocked, this should resolve the issue.

Circulation pump motor

1. Locate the circulation pump motor: The motor is typically located beneath the dishwasher and may require removing the bottom panel to access it.
2. Inspect the motor: Check the motor for any visible damage, wear, or unusual buildup around the motor shaft.
3. Test the motor: Using a multimeter, test the motor for continuity. If there’s no continuity, the motor may be faulty and need replacement.
4. Check for obstructions: Clear any debris around the motor that may be causing it to strain, leading to the humming sound.
5. Test it out: After cleaning and/or replacing the motor, run a cycle to check if the humming noise is gone. If the motor was faulty, replacing it should eliminate the noise.

Read more: how to replace a dishwasher circulation pump and motor.

More help where you need it

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