The Bosch Dishwasher E1 Error Code signals a problem with the water heating system. This guide will walk you through the steps to accurately diagnose and repair the components, ensuring your dishwasher returns to optimal working condition.

Tools and Materials Needed

Before you begin, make sure you have the following tools and materials ready:

• T-20 Torx screwdriver and flathead screwdriver
• Multimeter (for testing electrical components)
• Replacement parts (if necessary)
• Needle-nose pliers

Step 1: Access the Control Module

Begin by unplugging the dishwasher from the power source to ensure safety. Next, remove the T-20 Torx screws located on the inner door to detach the fascia panel. Carefully note the wiring connections on the control module, and consider taking a photo for easy reference during reassembly. Disconnect the wiring, then use a flathead screwdriver to gently pry out the metal tabs holding the module to the console assembly. Finally, carefully release the plastic tabs and slide the module out of the console.

Step 2: Check the Amperage

CAUTION: LIVE ELECTRICAL TESTING - This step requires the dishwasher to be plugged in and powered on, which exposes you to live electrical current. Extreme caution is necessary to avoid electric shock, which could result in serious injury. If you are uncomfortable with live voltage testing, do not proceed.

With the dishwasher plugged in and turned on, set your multimeter to measure Amps (AC):

1. Measure the current on the black wire using the meter probes. The reading should be approximately 11 Amps. The heater has failed if the reading is significantly lower, around 1.5 Amps.
2. Measure the current on the red heater wire at the control module. It should show around 9.5 Amps.
3. The voltage at the wire connection on the control module is measured.

A reading of 0 VAC indicates that the heater relay on the main control module unit has failed. If the voltage is around 120 VAC, you can proceed to the next step.

Step 3: Access the Heater

After completing the amperage checks:

1. Unplug the dishwasher again.
2. Carefully remove the dishwasher from its cabinet and lay it on its back, being mindful of any residual water that may spill from the sump or hoses—keep a towel handy.
3. Remove the door springs from the base and disconnect the door cables.
4. Remove the terminal block wiring connectors from the base and disconnect the hose from the water valve. You can remove the water valve from the base for easier access.
5. Disconnect the J-box ground wire and pull the cables out of the J-box.
6. Pull out the inlet hose from the sump and carefully separate the base from the tank and sump.
7. Remove the two T-20 Torx screws securing the heater assembly to the sump.
8. Note the wiring connections to the heater, flow switch, NTC (thermistor), and high-limit thermostat—taking a photo is recommended.
9. Disconnect these wires, gently pull the clips, and remove the heater assembly from the sump and pump.

Step 4: Test the Heater

With the heater assembly removed, set your multimeter to resistance mode (Ω). Use the probes to measure the resistance at the heater terminals. If the multimeter reads infinite resistance (∞), the heater has failed (open circuit) and needs to be replaced. If the reading is close to 0Ω, the heater has shorted and needs replacing. A typical resistance reading for the heater should be around 11Ω.

Next, check the resistance of the high-limit thermostat and circulation pump. If any of these components show infinite resistance (∞), they are faulty and should be replaced. The high-limit thermostat should have a resistance of around 0.3Ω .

If the heater, thermostat and circulation pump are all functioning correctly, inspect the wire harnesses for any signs of damage, such as fraying, tears, or burn marks. Replace any damaged wiring as necessary. If all components and wiring pass inspection and testing, but the E1 error persists, replacing the control module should be considered a last resort.

By following these detailed steps, you can accurately diagnose and repair the root causes of the Bosch Dishwasher E1 Error Code, restoring your appliance to full functionality.