Viessmann Water Softeners Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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bP
Display shows 'bP' or similar, and the unit indicates bypass mode.
Bypass Mode Active
E1
Display shows E1 and the backlight flashes; the softener is unresponsive.
General Controller Communication Error
E2
Display shows E2 and the unit cannot be programmed.
Keypad / Button Fault
E3
Display shows E3 and the unit indicates a sensor bus error (for models with multiple sensors).
Sensor Bus Communication Fault
E4
Display shows E4, and the unit reports a power supply error.
Low Voltage / Power Supply Fault
E5
Display shows E5, and the unit indicates a configuration mismatch.
Configuration / Model Mismatch Fault
F1
Display shows F1 and the softener does not regenerate automatically.
Flow Sensor Signal Fault
F10
Display shows F10 and no salt consumption is observed over time.
Brine System Not Operating
F11
Display shows F11 and water remains hard even after regeneration.
Resin Capacity / Exhaustion Fault
F12
Display shows F12 and the unit reports low salt even when the tank is full.
Salt Level Sensor Fault
F13
Display shows F13 and the unit will not enter regeneration when commanded.
Regeneration Start Inhibit / Safety Interlock Fault
F14
Display shows F14 and the unit indicates a sensor temperature error.
Temperature Sensor Fault
F15
Display shows F15 and the unit reports an internal memory error.
EEPROM / Configuration Memory Fault
F2
Display shows F2, and regeneration stops shortly after starting.
Brine Tank Level / Brine Draw Fault
F3
Display shows F3, and the unit remains in service mode without regenerating.
Motor / Valve Drive Fault
F4
Display shows F4, and the softener is stuck in one regeneration step.
Position Switch / Encoder Fault
F5
Display shows F5, and no water is delivered through the softener.
Inlet / Outlet Pressure or Flow Fault
F6
Display shows F6, and the unit does not count down remaining capacity correctly.
Metering / Volume Calculation Fault
F7
Display shows F7, and regeneration does not start at the programmed time.
Real-Time Clock / Timer Fault
F8
Display shows F8, and the unit aborts regeneration with an alarm.
Drain Line / Backwash Flow Fault
F9
Display shows F9 and the softener remains in regeneration indefinitely.
Regeneration Step Timeout
Lo
Display shows 'Lo' or a low salt icon, and an audible alarm sounds.
Low Salt Level Warning
Symptom
Brine tank overfills with water after regeneration
Brine Refill / Float Valve Malfunction
Symptom
Brine tank remains dry; no water in bottom even after refill stage
No Brine Refill
Symptom
Display is on but unresponsive or frozen; buttons do not work.
Controller Freeze / User Interface Lockup
Symptom
Loud banging or knocking noises in pipes when the softener regenerates.
Water Hammer During Regeneration
Symptom
Softener causes low water pressure in the house during normal operation.
Flow Restriction Through Softener
Symptom
Softener causes noticeable vibration and rattling in nearby pipes during regeneration.
Hydraulic Vibration / Flow Pulsation
Symptom
Softener causes very low or no water flow during regeneration.
Regeneration Flow Restriction
Symptom
Softener display backlight flickers or dims intermittently
Unstable Low-Voltage Supply
Symptom
Softener emits a foul or musty odor from the brine tank
Biological Growth in Brine Tank
Symptom
Softener emits a persistent humming noise even when not regenerating.
Transformer / Motor Hum
Symptom
Softener emits a plastic or burning smell from the control head area
Overheating Electrical Component
Symptom
Softener frequently loses time and settings after short power outages
Backup Power / Memory Retention Failure
Symptom
Softener makes grinding or clicking noises from the valve head during operation.
Valve Motor / Gear Train Wear
Symptom
Softener produces cloudy or discolored water after regeneration
Resin or Sediment Discharge
Symptom
Softener produces salty-tasting water immediately after regeneration
Excessive Brine Carryover
Symptom
Softener stuck in regeneration; continues cycling water to drain for many hours.
Regeneration Not Completing
Symptom
Softener will not power on; display is blank.
No Power / Dead Control
Symptom
The softener does not regenerate at all, but no error codes are displayed.
Regeneration Not Initiating
Symptom
The softener regenerates too frequently, causing excessive salt and water consumption.
Over-Regeneration / Incorrect Programming
Symptom
The softener uses no salt over weeks of operation, but no alarms are shown.
Brine System Non-Function Without Error
Symptom
The water softener leaks from around the valve head or top cover.
Valve Head / O-Ring Leakage
Symptom
The water softener leaks from the brine tank or around the brine well.
Brine Tank / Brine Well Leakage
Symptom
Water remains hard at taps even though the softener appears to run normally (no error code).
Ineffective Softening / Resin Exhaustion
Symptom
Water softener leaks from the drain hose during normal service (not regenerating).
Internal Valve Bypass to Drain
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| bP |
Display shows 'bP' or similar, and the unit indicates bypass mode.
|
Bypass Mode Active | View Details |
| E1 |
Display shows E1 and the backlight flashes; the softener is unresponsive.
|
General Controller Communication Error | View Details |
| E2 |
Display shows E2 and the unit cannot be programmed.
|
Keypad / Button Fault | View Details |
| E3 |
Display shows E3 and the unit indicates a sensor bus error (for models with multiple sensors).
|
Sensor Bus Communication Fault | View Details |
| E4 |
Display shows E4, and the unit reports a power supply error.
|
Low Voltage / Power Supply Fault | View Details |
| E5 |
Display shows E5, and the unit indicates a configuration mismatch.
|
Configuration / Model Mismatch Fault | View Details |
| F1 |
Display shows F1 and the softener does not regenerate automatically.
|
Flow Sensor Signal Fault | View Details |
| F10 |
Display shows F10 and no salt consumption is observed over time.
|
Brine System Not Operating | View Details |
| F11 |
Display shows F11 and water remains hard even after regeneration.
|
Resin Capacity / Exhaustion Fault | View Details |
| F12 |
Display shows F12 and the unit reports low salt even when the tank is full.
|
Salt Level Sensor Fault | View Details |
| F13 |
Display shows F13 and the unit will not enter regeneration when commanded.
|
Regeneration Start Inhibit / Safety Interlock Fault | View Details |
| F14 |
Display shows F14 and the unit indicates a sensor temperature error.
|
Temperature Sensor Fault | View Details |
| F15 |
Display shows F15 and the unit reports an internal memory error.
|
EEPROM / Configuration Memory Fault | View Details |
| F2 |
Display shows F2, and regeneration stops shortly after starting.
|
Brine Tank Level / Brine Draw Fault | View Details |
| F3 |
Display shows F3, and the unit remains in service mode without regenerating.
|
Motor / Valve Drive Fault | View Details |
| F4 |
Display shows F4, and the softener is stuck in one regeneration step.
|
Position Switch / Encoder Fault | View Details |
| F5 |
Display shows F5, and no water is delivered through the softener.
|
Inlet / Outlet Pressure or Flow Fault | View Details |
| F6 |
Display shows F6, and the unit does not count down remaining capacity correctly.
|
Metering / Volume Calculation Fault | View Details |
| F7 |
Display shows F7, and regeneration does not start at the programmed time.
|
Real-Time Clock / Timer Fault | View Details |
| F8 |
Display shows F8, and the unit aborts regeneration with an alarm.
|
Drain Line / Backwash Flow Fault | View Details |
| F9 |
Display shows F9 and the softener remains in regeneration indefinitely.
|
Regeneration Step Timeout | View Details |
| Lo |
Display shows 'Lo' or a low salt icon, and an audible alarm sounds.
|
Low Salt Level Warning | View Details |
| – |
Brine tank overfills with water after regeneration
|
Brine Refill / Float Valve Malfunction | View Details |
| – |
Brine tank remains dry; no water in bottom even after refill stage
|
No Brine Refill | View Details |
| – |
Display is on but unresponsive or frozen; buttons do not work.
|
Controller Freeze / User Interface Lockup | View Details |
| – |
Loud banging or knocking noises in pipes when the softener regenerates.
|
Water Hammer During Regeneration | View Details |
| – |
Softener causes low water pressure in the house during normal operation.
|
Flow Restriction Through Softener | View Details |
| – |
Softener causes noticeable vibration and rattling in nearby pipes during regeneration.
|
Hydraulic Vibration / Flow Pulsation | View Details |
| – |
Softener causes very low or no water flow during regeneration.
|
Regeneration Flow Restriction | View Details |
| – |
Softener display backlight flickers or dims intermittently
|
Unstable Low-Voltage Supply | View Details |
| – |
Softener emits a foul or musty odor from the brine tank
|
Biological Growth in Brine Tank | View Details |
| – |
Softener emits a persistent humming noise even when not regenerating.
|
Transformer / Motor Hum | View Details |
| – |
Softener emits a plastic or burning smell from the control head area
|
Overheating Electrical Component | View Details |
| – |
Softener frequently loses time and settings after short power outages
|
Backup Power / Memory Retention Failure | View Details |
| – |
Softener makes grinding or clicking noises from the valve head during operation.
|
Valve Motor / Gear Train Wear | View Details |
| – |
Softener produces cloudy or discolored water after regeneration
|
Resin or Sediment Discharge | View Details |
| – |
Softener produces salty-tasting water immediately after regeneration
|
Excessive Brine Carryover | View Details |
| – |
Softener stuck in regeneration; continues cycling water to drain for many hours.
|
Regeneration Not Completing | View Details |
| – |
Softener will not power on; display is blank.
|
No Power / Dead Control | View Details |
| – |
The softener does not regenerate at all, but no error codes are displayed.
|
Regeneration Not Initiating | View Details |
| – |
The softener regenerates too frequently, causing excessive salt and water consumption.
|
Over-Regeneration / Incorrect Programming | View Details |
| – |
The softener uses no salt over weeks of operation, but no alarms are shown.
|
Brine System Non-Function Without Error | View Details |
| – |
The water softener leaks from around the valve head or top cover.
|
Valve Head / O-Ring Leakage | View Details |
| – |
The water softener leaks from the brine tank or around the brine well.
|
Brine Tank / Brine Well Leakage | View Details |
| – |
Water remains hard at taps even though the softener appears to run normally (no error code).
|
Ineffective Softening / Resin Exhaustion | View Details |
| – |
Water softener leaks from the drain hose during normal service (not regenerating).
|
Internal Valve Bypass to Drain | View Details |
No matching codes found
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