E43
Bosch Dishwasher
Severity: ModerateWhat Does This Error Mean?
The E43 error on a Bosch dishwasher indicates a fault with the control board relay — specifically the relay that controls power to the wash motor or heating element. A relay is an electronic switch on the control board. When it fails to open or close as commanded, the dishwasher cannot safely control the motor or heating circuit, and E43 is logged. This is typically a control board issue that requires professional diagnosis or board replacement.
Affected Models
- SHPM88Z75N
- SHPM65Z55N
- SHEM63W55N
- SHDX5EM3N
- SHP865ZD5N
- Most Bosch 500 and 800 series dishwashers
Common Causes
- Relay on the control board has failed in the open or closed position
- Relay contacts have burned or corroded from years of cycling on and off
- Power surge damaged the relay on the control board
- Wiring harness connected to the relay output has a short or open circuit
- Control board has a broader internal failure affecting the relay driver circuit
How to Fix It
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Turn off the dishwasher at the circuit breaker for 10 full minutes. Restore power and run a short cycle to see if E43 clears. A relay that stuck due to a temporary voltage spike sometimes resets with a full power cycle.
If E43 returns immediately or within the first minute of the cycle, the relay fault is persistent and needs hands-on diagnosis.
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Inspect the power supply to the dishwasher. Check that the dedicated circuit is providing a stable 120V supply. Voltage fluctuations or a loose connection at the junction box can cause relay errors on Bosch dishwashers.
If other appliances on the same circuit behave erratically, the house wiring may have a problem worth checking with an electrician.
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Check the wiring harness connections at the control board. With power OFF at the breaker, locate the control board (typically in the door panel behind the inner door liner). Reseat each connector firmly.
Wiring problems that mimic relay faults are worth ruling out before spending money on a new board.
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If accessible, listen for the relay clicking during a cycle. A relay in good condition makes a clear click when it switches. A relay that buzzes, clicks rapidly, or is completely silent when it should activate is suspect.
This diagnostic step requires some experience with appliance internals. If you are not comfortable, leave this to a technician.
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Have a technician replace the control board if the relay is confirmed faulty. In most cases, individual relay replacement on Bosch boards is not practical — the entire board is replaced as a unit.
Ensure the replacement board is the correct part number for your specific Bosch model. Using your model number (found on the door frame label) when ordering guarantees compatibility.
When to Call a Professional
E43 almost always requires a technician to diagnose properly. A technician can measure relay output voltage to confirm whether the relay or its driver circuit has failed. Bosch control board replacement typically costs $150 to $350 in parts, plus $75 to $150 in labor. Always get a diagnosis before purchasing a board.
Frequently Asked Questions
What is a relay and why does it matter in a dishwasher?
A relay is an electronic switch — when the control board sends a signal, the relay either connects or disconnects power to a component (like the motor or heater). When a relay fails, the component it controls either gets stuck on or cannot turn on at all. Bosch dishwashers have several relays on the main board, each controlling a different function.
Can E43 cause the dishwasher to stop mid-cycle?
Yes. If the relay fault occurs while the dishwasher is running, the machine will stop and display E43. The cycle will not resume until the fault is resolved. Food and water may be left inside the machine — this is safe for short periods but should be addressed promptly.
How long does a Bosch dishwasher control board last?
Under normal use, a Bosch control board typically lasts 8 to 15 years. Power surges, water damage, and excessive heat can shorten board life significantly. Using a surge protector on the dishwasher outlet can help protect the board from electrical spikes.