H11
Bosch Flow Sensor / Flow Switch Fault (Electric Model)

Bosch electric water heater displays H11; unit does not energize heating elements

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Stuck flow switch, Scaled or obstructed flow sensor, Loose wiring to flow sensor, Defective flow detection circuit

How to Fix / Troubleshooting

Safety first: Turn OFF power at the breaker and close the water supply before servicing.

  • Clean inlet filter: Remove and clean the cold water inlet filter screen to ensure adequate flow.
  • Inspect flow sensor or switch: Locate the flow sensor assembly on the inlet side. Remove it per the manual and check for debris or scale preventing movement. Clean gently.
  • Check wiring: Ensure the flow sensor wiring harness is intact and firmly connected to the control board.
  • Test operation: Restore water and power, then open a hot tap. If H11 persists, the flow sensor or control board may need replacement.
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Repair Difficulty

Medium 3/5

Required Part

Flow Switch / Flow Sensor Assembly
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