Fafco
Fafco Pool Heaters Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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bYP
Display shows bYP or BYPASS ONLY; system refuses to send water to solar panels.
Forced Bypass / Service Mode
dIF
Controller shows dIF or DELTA ERROR; solar does not engage even on sunny days.
Temperature Differential Logic Fault
Er1
Controller displays Er1 and solar heating is disabled.
Pool Temperature Sensor Open Circuit
Er2
Controller displays Er2 and solar heating is disabled.
Roof / Collector Temperature Sensor Open Circuit
Er3
Controller displays Er3; temperatures shown are unrealistic and system may behave erratically.
Temperature Sensor Short Circuit
Er4
Controller displays Er4; solar valve and pump do not respond correctly.
Internal Controller Communication Fault
FLO
Display shows FLO and heater will not start; solar pump does not run or shuts off quickly.
Low Water Flow Fault
FrE
Display shows FrE or FREEZE; system runs unexpectedly at low temperatures or locks out solar heating.
Freeze Protection Mode Activation
HLO
Controller displays HLO or HIGH LIMIT and shuts down solar heating; water circulation continues but panels are bypassed.
High Temperature Limit Trip
HPC
Display shows HPC or HIGH PRESSURE; solar heating shuts down and bypasses panels.
High Pressure Protection Trip
LOC
Display shows LOC or LOCK; settings cannot be changed and some functions are disabled.
Controller Keypad Lockout
LOP
Controller shows LOP or LOW PRESSURE; system shuts off solar pump to protect panels.
Low Pressure / Suction Fault
PMP
Controller shows PMP or PUMP ERROR; solar pump output does not energize.
Solar Pump Relay Fault
PSE
Display shows PSE or PUMP SENSOR ERROR; solar pump does not start or shuts down immediately.
Pump Feedback / Current Sense Fault
rES
Controller repeatedly shows rES or RESET REQUIRED and will not stay in AUTO mode.
Controller Configuration / Memory Fault
SEN
Controller shows SEN or SENSOR ERROR; solar heating is disabled and system runs in bypass only.
Temperature Sensor Circuit Fault
tSt
Controller stuck showing tSt or TEST and does not operate solar heating normally.
Controller Test Mode Engaged
VAL
Controller displays VAL or VALVE ERROR; solar valve does not move or stops mid-position.
Solar Valve Actuator Fault
Symptom
Controller display is blank or very dim; solar system does not respond.
Controller Power Loss
Symptom
Controller display works but buttons do not respond or respond intermittently.
Keypad / User Interface Failure
Symptom
Main pool pump loses prime or sucks air whenever solar is activated.
Air Ingress in Solar Suction or Return
Symptom
Pool is not warming up even on sunny days; solar system appears to run normally.
Insufficient Solar Heat Transfer
Symptom
Solar controller emits a burning smell or shows visible scorch marks inside.
Controller Overheating or Component Failure
Symptom
Solar panels leak water on the roof or at header manifolds when the pump is running.
Collector Panel Manifold Leak
Symptom
Solar panels make loud popping or ticking noises when heating up or cooling down.
Thermal Expansion Noise in Collectors and Plumbing
Symptom
Solar panels show visible sagging, warping, or detachment from roof anchors.
Panel Mounting Hardware Failure
Symptom
Solar pump is very noisy, vibrates, or runs hot when feeding Fafco panels.
Solar Booster Pump Mechanical Wear or Cavitation
Symptom
Solar pump runs but there is little or no flow through the Fafco panels.
Solar Loop Flow Restriction
Symptom
Solar return water is excessively hot, causing uncomfortable pool temperature spikes.
Overheating Due to Control Misconfiguration
Symptom
Solar system causes frequent trips of the electrical breaker when starting.
Electrical Overload or Short in Solar Pump Circuit
Symptom
Solar system intermittently turns on and off rapidly, cycling the valve and pump.
Control Hunting / Unstable Temperature Differential
Symptom
Solar system never turns on, even when pool is cold and sunny conditions exist.
Control Enable / Interlock Issue
Symptom
Solar system runs at night, cooling the pool instead of heating it.
Reversed Sensor Logic or Miswired Sensors
Symptom
Solar valve actuator turns continuously or stops in the wrong position, causing incorrect flow.
Valve Actuator Limit Switch Failure
Symptom
Visible algae or dirt buildup inside clear Fafco panel tubes, reducing performance.
Internal Collector Fouling
Symptom
Water appears to drain backwards from the roof into the pool equipment when the system shuts off.
Check Valve Failure on Solar Return
Symptom
Water drips from roof area only when solar is off and panels are draining.
Drain-Down Check Valve or Vacuum Breaker Leak
Symptom
Water hammer or banging noises occur in pipes when solar turns on or off.
Hydraulic Shock in Solar Plumbing
Symptom
Water leaks at the equipment pad around the Fafco solar manifold when solar is on.
Manifold Union or Gasket Leak
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| bYP |
Display shows bYP or BYPASS ONLY; system refuses to send water to solar panels.
|
Forced Bypass / Service Mode | View Details |
| dIF |
Controller shows dIF or DELTA ERROR; solar does not engage even on sunny days.
|
Temperature Differential Logic Fault | View Details |
| Er1 |
Controller displays Er1 and solar heating is disabled.
|
Pool Temperature Sensor Open Circuit | View Details |
| Er2 |
Controller displays Er2 and solar heating is disabled.
|
Roof / Collector Temperature Sensor Open Circuit | View Details |
| Er3 |
Controller displays Er3; temperatures shown are unrealistic and system may behave erratically.
|
Temperature Sensor Short Circuit | View Details |
| Er4 |
Controller displays Er4; solar valve and pump do not respond correctly.
|
Internal Controller Communication Fault | View Details |
| FLO |
Display shows FLO and heater will not start; solar pump does not run or shuts off quickly.
|
Low Water Flow Fault | View Details |
| FrE |
Display shows FrE or FREEZE; system runs unexpectedly at low temperatures or locks out solar heating.
|
Freeze Protection Mode Activation | View Details |
| HLO |
Controller displays HLO or HIGH LIMIT and shuts down solar heating; water circulation continues but panels are bypassed.
|
High Temperature Limit Trip | View Details |
| HPC |
Display shows HPC or HIGH PRESSURE; solar heating shuts down and bypasses panels.
|
High Pressure Protection Trip | View Details |
| LOC |
Display shows LOC or LOCK; settings cannot be changed and some functions are disabled.
|
Controller Keypad Lockout | View Details |
| LOP |
Controller shows LOP or LOW PRESSURE; system shuts off solar pump to protect panels.
|
Low Pressure / Suction Fault | View Details |
| PMP |
Controller shows PMP or PUMP ERROR; solar pump output does not energize.
|
Solar Pump Relay Fault | View Details |
| PSE |
Display shows PSE or PUMP SENSOR ERROR; solar pump does not start or shuts down immediately.
|
Pump Feedback / Current Sense Fault | View Details |
| rES |
Controller repeatedly shows rES or RESET REQUIRED and will not stay in AUTO mode.
|
Controller Configuration / Memory Fault | View Details |
| SEN |
Controller shows SEN or SENSOR ERROR; solar heating is disabled and system runs in bypass only.
|
Temperature Sensor Circuit Fault | View Details |
| tSt |
Controller stuck showing tSt or TEST and does not operate solar heating normally.
|
Controller Test Mode Engaged | View Details |
| VAL |
Controller displays VAL or VALVE ERROR; solar valve does not move or stops mid-position.
|
Solar Valve Actuator Fault | View Details |
| – |
Controller display is blank or very dim; solar system does not respond.
|
Controller Power Loss | View Details |
| – |
Controller display works but buttons do not respond or respond intermittently.
|
Keypad / User Interface Failure | View Details |
| – |
Main pool pump loses prime or sucks air whenever solar is activated.
|
Air Ingress in Solar Suction or Return | View Details |
| – |
Pool is not warming up even on sunny days; solar system appears to run normally.
|
Insufficient Solar Heat Transfer | View Details |
| – |
Solar controller emits a burning smell or shows visible scorch marks inside.
|
Controller Overheating or Component Failure | View Details |
| – |
Solar panels leak water on the roof or at header manifolds when the pump is running.
|
Collector Panel Manifold Leak | View Details |
| – |
Solar panels make loud popping or ticking noises when heating up or cooling down.
|
Thermal Expansion Noise in Collectors and Plumbing | View Details |
| – |
Solar panels show visible sagging, warping, or detachment from roof anchors.
|
Panel Mounting Hardware Failure | View Details |
| – |
Solar pump is very noisy, vibrates, or runs hot when feeding Fafco panels.
|
Solar Booster Pump Mechanical Wear or Cavitation | View Details |
| – |
Solar pump runs but there is little or no flow through the Fafco panels.
|
Solar Loop Flow Restriction | View Details |
| – |
Solar return water is excessively hot, causing uncomfortable pool temperature spikes.
|
Overheating Due to Control Misconfiguration | View Details |
| – |
Solar system causes frequent trips of the electrical breaker when starting.
|
Electrical Overload or Short in Solar Pump Circuit | View Details |
| – |
Solar system intermittently turns on and off rapidly, cycling the valve and pump.
|
Control Hunting / Unstable Temperature Differential | View Details |
| – |
Solar system never turns on, even when pool is cold and sunny conditions exist.
|
Control Enable / Interlock Issue | View Details |
| – |
Solar system runs at night, cooling the pool instead of heating it.
|
Reversed Sensor Logic or Miswired Sensors | View Details |
| – |
Solar valve actuator turns continuously or stops in the wrong position, causing incorrect flow.
|
Valve Actuator Limit Switch Failure | View Details |
| – |
Visible algae or dirt buildup inside clear Fafco panel tubes, reducing performance.
|
Internal Collector Fouling | View Details |
| – |
Water appears to drain backwards from the roof into the pool equipment when the system shuts off.
|
Check Valve Failure on Solar Return | View Details |
| – |
Water drips from roof area only when solar is off and panels are draining.
|
Drain-Down Check Valve or Vacuum Breaker Leak | View Details |
| – |
Water hammer or banging noises occur in pipes when solar turns on or off.
|
Hydraulic Shock in Solar Plumbing | View Details |
| – |
Water leaks at the equipment pad around the Fafco solar manifold when solar is on.
|
Manifold Union or Gasket Leak | View Details |
No matching codes found
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