AO Smith
AO Smith Pool Pumps Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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ERR1
Digital AO Smith variable-speed pool pump will not start; control shows “ERR1” shortly after power-up.
Low Line Voltage / Undervoltage Protection
ERR2
AO Smith variable-speed pool pump stops running and displays “ERR2” on the control panel.
Overvoltage Protection / High Line Voltage
ERR3
AO Smith variable-speed pool pump attempts to start, then shuts down with “ERR3” on the display.
Overcurrent / Motor Overload Trip
ERR4
AO Smith variable-speed pool pump shows “ERR4” and will not run; sometimes appears after a thunderstorm or power surge.
Internal Drive Fault / Control Board Failure
ERR5
AO Smith variable-speed pool pump runs briefly, then stops and displays “ERR5”.
Overtemperature / Drive Overheat
ERR6
AO Smith variable-speed pool pump display shows “ERR6” and the motor does not start.
Motor Stall / Rotor Lock Detection
ERR7
AO Smith variable-speed pool pump intermittently stops and shows “ERR7” on the keypad.
Communication Error Between Keypad and Drive
ERR8
AO Smith variable-speed pool pump shows “ERR8” and will not respond to speed commands.
Internal Memory / Parameter Error
ERR9
AO Smith variable-speed pool pump display shows “ERR9” and the motor does not run.
Ground Fault / Leakage Current Detected
LOC
AO Smith variable-speed pool pump display shows “LOC” and buttons do not respond.
Keypad Lockout / Child Lock Enabled
OFF
AO Smith variable-speed pool pump display shows “OFF” and pump does not run even though power is present.
Standby Mode / External Control Off
Symptom
AO Smith pool pump emits a loud banging or knocking noise when starting or stopping.
Water Hammer / Loose Mounting
Symptom
AO Smith pool pump hums but will not start; motor housing gets warm and then shuts off.
Failed Start Capacitor or Centrifugal Switch (Single-Speed / Two-Speed Motors)
Symptom
AO Smith pool pump leaks at the clear lid on top of the pump strainer basket.
Pump Lid Seal Failure
Symptom
AO Smith pool pump leaks at the union connections near the pump inlet or outlet.
Union Gasket Failure / Misalignment
Symptom
AO Smith pool pump leaks water between the pump housing and the motor, often dripping from the bottom of the motor.
Failed Mechanical Shaft Seal
Symptom
AO Smith pool pump loses prime overnight and must be manually primed each day.
Suction-Side Air Leak / Check Valve Failure
Symptom
AO Smith pool pump makes a loud rattling or grinding noise from the wet end when running.
Cavitation or Debris in Impeller
Symptom
AO Smith pool pump motor cycles on and off repeatedly during operation without tripping the breaker.
Internal Thermal Protector Cycling
Symptom
AO Smith pool pump motor emits a burning smell or visible smoke shortly after starting.
Motor Winding Overheating / Electrical Short
Symptom
AO Smith pool pump motor overheats and shuts off after running for a short time, then restarts after cooling.
Thermal Overload Tripping
Symptom
AO Smith pool pump motor runs in the wrong direction (for reversible models or after wiring changes).
Incorrect Rotation
Symptom
AO Smith pool pump motor shaft is rusted or corroded near the seal area, making seal replacement difficult.
Shaft Corrosion at Seal Surface
Symptom
AO Smith pool pump produces a high-pitched whine from the drive area on a variable-speed model, especially at certain speeds.
Inverter Switching Noise / Resonance
Symptom
AO Smith pool pump runs but filter pressure is very high and flow at returns is weak.
Discharge Restriction / Overloaded Pump
Symptom
AO Smith pool pump runs but is very loud, with a high-pitched whine or grinding noise from the motor end.
Worn Motor Bearings
Symptom
AO Smith pool pump runs but pressure at the filter gauge is very low and returns are weak.
Suction Restriction or Impeller Clogging
Symptom
AO Smith pool pump runs but there is little or no water flow; pump basket does not fill completely.
Loss of Prime / Suction Restriction
Symptom
AO Smith pool pump runs but water appears cloudy or circulation seems inadequate despite normal pressure.
Insufficient Run Time or Incorrect Speed Programming (Variable-Speed)
Symptom
AO Smith pool pump trips the circuit breaker or GFCI immediately or within a few seconds of starting.
Short Circuit or Ground Fault
Symptom
AO Smith pool pump vibrates excessively and may move slightly on the pad during operation.
Imbalance or Misalignment
Symptom
AO Smith pool pump will not run at all; no humming, no movement, but power is present at the equipment pad.
Open Circuit / No Power to Motor
Symptom
AO Smith two-speed pool pump will only run on high speed; low speed does not work.
Low-Speed Circuit Failure
Symptom
AO Smith two-speed pool pump will only run on low speed; high speed does not engage.
High-Speed Circuit Failure
Symptom
AO Smith variable-speed pool pump display is blank, but line voltage is present at the motor.
No Display / Dead Control Panel
Symptom
AO Smith variable-speed pool pump does not respond to speed changes from the keypad; stays at one speed.
Control Interface or Drive Logic Fault
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| ERR1 |
Digital AO Smith variable-speed pool pump will not start; control shows “ERR1” shortly after power-up.
|
Low Line Voltage / Undervoltage Protection | View Details |
| ERR2 |
AO Smith variable-speed pool pump stops running and displays “ERR2” on the control panel.
|
Overvoltage Protection / High Line Voltage | View Details |
| ERR3 |
AO Smith variable-speed pool pump attempts to start, then shuts down with “ERR3” on the display.
|
Overcurrent / Motor Overload Trip | View Details |
| ERR4 |
AO Smith variable-speed pool pump shows “ERR4” and will not run; sometimes appears after a thunderstorm or power surge.
|
Internal Drive Fault / Control Board Failure | View Details |
| ERR5 |
AO Smith variable-speed pool pump runs briefly, then stops and displays “ERR5”.
|
Overtemperature / Drive Overheat | View Details |
| ERR6 |
AO Smith variable-speed pool pump display shows “ERR6” and the motor does not start.
|
Motor Stall / Rotor Lock Detection | View Details |
| ERR7 |
AO Smith variable-speed pool pump intermittently stops and shows “ERR7” on the keypad.
|
Communication Error Between Keypad and Drive | View Details |
| ERR8 |
AO Smith variable-speed pool pump shows “ERR8” and will not respond to speed commands.
|
Internal Memory / Parameter Error | View Details |
| ERR9 |
AO Smith variable-speed pool pump display shows “ERR9” and the motor does not run.
|
Ground Fault / Leakage Current Detected | View Details |
| LOC |
AO Smith variable-speed pool pump display shows “LOC” and buttons do not respond.
|
Keypad Lockout / Child Lock Enabled | View Details |
| OFF |
AO Smith variable-speed pool pump display shows “OFF” and pump does not run even though power is present.
|
Standby Mode / External Control Off | View Details |
| – |
AO Smith pool pump emits a loud banging or knocking noise when starting or stopping.
|
Water Hammer / Loose Mounting | View Details |
| – |
AO Smith pool pump hums but will not start; motor housing gets warm and then shuts off.
|
Failed Start Capacitor or Centrifugal Switch (Single-Speed / Two-Speed Motors) | View Details |
| – |
AO Smith pool pump leaks at the clear lid on top of the pump strainer basket.
|
Pump Lid Seal Failure | View Details |
| – |
AO Smith pool pump leaks at the union connections near the pump inlet or outlet.
|
Union Gasket Failure / Misalignment | View Details |
| – |
AO Smith pool pump leaks water between the pump housing and the motor, often dripping from the bottom of the motor.
|
Failed Mechanical Shaft Seal | View Details |
| – |
AO Smith pool pump loses prime overnight and must be manually primed each day.
|
Suction-Side Air Leak / Check Valve Failure | View Details |
| – |
AO Smith pool pump makes a loud rattling or grinding noise from the wet end when running.
|
Cavitation or Debris in Impeller | View Details |
| – |
AO Smith pool pump motor cycles on and off repeatedly during operation without tripping the breaker.
|
Internal Thermal Protector Cycling | View Details |
| – |
AO Smith pool pump motor emits a burning smell or visible smoke shortly after starting.
|
Motor Winding Overheating / Electrical Short | View Details |
| – |
AO Smith pool pump motor overheats and shuts off after running for a short time, then restarts after cooling.
|
Thermal Overload Tripping | View Details |
| – |
AO Smith pool pump motor runs in the wrong direction (for reversible models or after wiring changes).
|
Incorrect Rotation | View Details |
| – |
AO Smith pool pump motor shaft is rusted or corroded near the seal area, making seal replacement difficult.
|
Shaft Corrosion at Seal Surface | View Details |
| – |
AO Smith pool pump produces a high-pitched whine from the drive area on a variable-speed model, especially at certain speeds.
|
Inverter Switching Noise / Resonance | View Details |
| – |
AO Smith pool pump runs but filter pressure is very high and flow at returns is weak.
|
Discharge Restriction / Overloaded Pump | View Details |
| – |
AO Smith pool pump runs but is very loud, with a high-pitched whine or grinding noise from the motor end.
|
Worn Motor Bearings | View Details |
| – |
AO Smith pool pump runs but pressure at the filter gauge is very low and returns are weak.
|
Suction Restriction or Impeller Clogging | View Details |
| – |
AO Smith pool pump runs but there is little or no water flow; pump basket does not fill completely.
|
Loss of Prime / Suction Restriction | View Details |
| – |
AO Smith pool pump runs but water appears cloudy or circulation seems inadequate despite normal pressure.
|
Insufficient Run Time or Incorrect Speed Programming (Variable-Speed) | View Details |
| – |
AO Smith pool pump trips the circuit breaker or GFCI immediately or within a few seconds of starting.
|
Short Circuit or Ground Fault | View Details |
| – |
AO Smith pool pump vibrates excessively and may move slightly on the pad during operation.
|
Imbalance or Misalignment | View Details |
| – |
AO Smith pool pump will not run at all; no humming, no movement, but power is present at the equipment pad.
|
Open Circuit / No Power to Motor | View Details |
| – |
AO Smith two-speed pool pump will only run on high speed; low speed does not work.
|
Low-Speed Circuit Failure | View Details |
| – |
AO Smith two-speed pool pump will only run on low speed; high speed does not engage.
|
High-Speed Circuit Failure | View Details |
| – |
AO Smith variable-speed pool pump display is blank, but line voltage is present at the motor.
|
No Display / Dead Control Panel | View Details |
| – |
AO Smith variable-speed pool pump does not respond to speed changes from the keypad; stays at one speed.
|
Control Interface or Drive Logic Fault | View Details |
No matching codes found
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