Error code reference

Bosch Dishwasher Error Code #H

Apexx display

Bosch codesBosch dishwasher codes

Apexx display: Heating system fault (heater, Hi-Limit, flow switch, NTC, control module heater relay).

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What #H means on a Bosch dishwasher

The #H error code on a Bosch dishwasher (Apexx display models) signals a heating system fault detected by the control module. The board monitors the heating circuit continuously and throws this code when it cannot confirm proper heater operation. The fault can originate from several components: the heating element itself, the hi-limit thermostat (which cuts power to the heater if temperatures exceed safe limits), the flow switch (which confirms water is present before heating begins), the NTC temperature sensor (which reports water temperature to the control board), or the heater relay on the control module that switches power to the heater.

For a homeowner, this means the dishwasher detected a problem with how it heats water. Your dishes may come out cold, wet, or with detergent residue because the machine cannot reach the temperatures needed to clean and dry properly. The machine shuts down heating as a safety measure to prevent overheating or running the element dry.

Because this code covers five distinct components, diagnosis requires a multimeter and some disassembly. A technician will typically test the NTC sensor resistance, check hi-limit continuity, verify the flow switch is operating, and inspect the heater element before suspecting the control module relay.

Source: manufacturer service documentation.

Common causes of #H

  1. 01

    Failed NTC temperature sensor

    Part replacement

    The NTC sensor reports water temperature to the control board. If it fails open, shorts, or drifts out of its resistance spec, the board cannot confirm proper heating and triggers #H.

  2. 02

    Tripped or failed hi-limit thermostat

    Part replacement

    The hi-limit thermostat is a safety cutout that interrupts the heater circuit if water or internal temperatures exceed a safe threshold. A tripped or failed hi-limit breaks the heating circuit, causing the control board to log a heating fault.

  3. 03

    Burned out or open heating element

    Part replacement

    The heating element can burn out or develop an open circuit over time, especially if the machine has run with low water levels. A failed element draws no current, and the control board detects the absence of heating activity and sets #H.

  4. 04

    Faulty flow switch or failed heater relay on control module

    Part replacement

    The flow switch confirms water flow is present before the board activates the heater. If the flow switch sticks open, the board will not energize the heater. Similarly, if the heater relay on the control module itself has failed, the heater never receives power regardless of the other components being intact.

See the test procedure for each cause

Frequently asked questions about #H

What does the #H error code mean on a Bosch dishwasher?
#H on a Bosch Apexx display dishwasher indicates a heating system fault. The control board has detected a problem somewhere in the heating circuit, which includes the heating element, the hi-limit thermostat, the flow switch, the NTC temperature sensor, or the heater relay on the control module. The code does not identify which component specifically has failed, so some diagnostic testing is required.
Can I still use my Bosch dishwasher when it shows the #H error?
Running the dishwasher with an active #H code is not recommended. Without a functioning heating system, the machine cannot reach the temperatures required to sanitize dishes or activate dishwasher detergent effectively. More critically, if the hi-limit or flow switch has failed in a way that leaves the heater energized without proper water flow, continuing to run the machine could damage internal components or create a safety hazard. Stop using the machine until the fault is diagnosed.
How do I fix the #H error code on my Bosch dishwasher?
Start by checking the NTC sensor with a multimeter for correct resistance at room temperature (typically around 10k ohms for Bosch NTC sensors, but verify against your model's service data). Then test the hi-limit thermostat for continuity and the heating element for continuity and correct resistance. Inspect the flow switch for mechanical function and electrical continuity. If all those components test good, the heater relay on the control module is the likely culprit and the module will need replacement. Each failed component requires a part replacement.
How much does it cost to repair a Bosch dishwasher with error code #H?
Repair cost depends entirely on which component has failed. An NTC sensor is typically the least expensive fix, with parts running $15 to $40 and minimal labor if you are comfortable with basic appliance disassembly. A heating element replacement runs $50 to $100 in parts. A hi-limit thermostat is inexpensive at $10 to $30. If the control module has a failed heater relay, module replacement is the most expensive outcome, often $150 to $300 in parts alone, making professional diagnosis worthwhile before committing to that repair.
Will resetting my Bosch dishwasher clear the #H error?
A reset may temporarily clear the #H code, but it will return as soon as the control board runs its heating circuit checks again during the next wash cycle. A reset does not fix the underlying component failure. Use the reset only as a way to confirm the code is reproducible, not as a repair.

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