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Heat pumps · Error codes · Samsung
E911Samsung

E911 on a Samsung heat pump: FLow Switch Open Error

Short answer

On a Samsung heat pump, E911 means: FLow Switch Open Error. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.

Reviewed 23 September 2026 · 5 sources

What it means

On the EHS Mono R290 (AE***CXYD*K and pump-integrated AE***CXYB*K)

The manual says: FLow Switch Open Error.

Part involved: Water pump and flow sensor/switch.

When it shows: Unit self-diagnosis: FLow Switch Open Error.

Likely causes:

  • Water flow too low or flow sensor/switch signal inconsistent with pump state: low system pressure, air in system, blocked strainer/filter, closed valve, pump fault, flow switch/sensor or PCB fault, or an external pump creating flow.
  • Engineer checks per Samsung service manual: Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves.

On the EHS Mono R32 (AE***RXYD*G)

The manual says: Low flow rate error: in case of low flow rate in 30 sec during water pump signals is ON(Starting); in case of low flow rate in 15 sec during water pump signals is ON(After starting).

Part involved: Water pump and flow sensor/switch.

When it shows: Unit self-diagnosis: Low flow rate error: in case of low flow rate in 30 sec during water pump signals is ON(Starting); in case of low flow rate in 15 sec during water pump signals is ON(After starting).

Likely causes:

  • Water flow too low or flow sensor/switch signal inconsistent with pump state: low system pressure, air in system, blocked strainer/filter, closed valve, pump fault, flow switch/sensor or PCB fault, or an external pump creating flow.
  • Engineer checks per Samsung service manual: Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves.

On the EHS Mono (R410A, AE***JXYD*H)

The manual says: Flow switch and water pump error (F/S signal is OFF for 10 sec. during the water pump signal is ON).

Part involved: Water pump and flow sensor/switch.

When it shows: Unit self-diagnosis: Flow switch and water pump error (F/S signal is OFF for 10 sec. during the water pump signal is ON).

Likely causes:

  • Water flow too low or flow sensor/switch signal inconsistent with pump state: low system pressure, air in system, blocked strainer/filter, closed valve, pump fault, flow switch/sensor or PCB fault, or an external pump creating flow.
  • Engineer checks per Samsung service manual: Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves.

On the EHS Split Generation 4 (AEX/AEN, 2014)

The manual says: Water pump & flow switch OFF: flow switch signal is off for 10 seconds while the water pump signal is ON.

Part involved: Water pump and flow sensor/switch.

When it shows: Unit self-diagnosis: Water pump & flow switch OFF: flow switch signal is off for 10 seconds while the water pump signal is ON.

Likely causes:

  • Water flow too low or flow sensor/switch signal inconsistent with pump state: low system pressure, air in system, blocked strainer/filter, closed valve, pump fault, flow switch/sensor or PCB fault, or an external pump creating flow.
  • Engineer checks per Samsung service manual: Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves.

On the EHS TDM Plus (R410A)

The manual says: Flow switch and water pump error (F/S signal is OFF for 15 sec. during the water pump signal is ON).

Part involved: Water pump and flow sensor/switch.

When it shows: Unit self-diagnosis: Flow switch and water pump error (F/S signal is OFF for 15 sec. during the water pump signal is ON).

Likely causes:

  • Water flow too low or flow sensor/switch signal inconsistent with pump state: low system pressure, air in system, blocked strainer/filter, closed valve, pump fault, flow switch/sensor or PCB fault, or an external pump creating flow.
  • Engineer checks per Samsung service manual: Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves.

Is it safe?

Does the heat pump stop?Yes
Engineer needed?Yes

The heat pump stops until the fault clears or is reset.

Resetting itself: unknown.

Manual reset: unknown.

What you can check

  • Note the full error code shown on the controller; check the heat pump breaker/isolator in the consumer unit is ON; check the heating system pressure gauge reading (typically 1-2 bar when cold; do not top up unless you have been shown how); check the filling loop is closed; then contact your installer or Samsung service; Samsung manuals do not describe a homeowner reset for this code.

What the engineer will check

  • Check flow sensor/switch connector on PBA, flow switch, water pump operation and water flow rate (min 7 or 12 LPM depending on model); check strainer/filter, air, closed valves. Any work inside casings, on PCBs, wiring, sensors, pumps, valves or refrigerant is engineer-only.

Who to ask for: Heat pump installer (wet system / hydraulics).

Certification: None specific (plumbing competence); competent electrical worker for pump/PCB electrical tests.

What you might notice

What owners and engineers report

8 owner and engineer reports mention this.

  • No heating on the EHS Mono R32 (AE***RXYD*G): 6 reports
  • Keeps stopping / cutting out on the EHS Mono R32 (AE***RXYD*G): 2 reports

Sources

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 23 September 2026