The Pentair SuperFlo VS, SuperFlo VST and Sta-Rite SuperMax VS share one drive and one manual. When the drive detects a problem, it shows a two-character fault code and the pump stops. Pentair's manual lists eleven codes. This guide goes through each one, what Pentair says to do, and where it stops being something to try yourself.

If you have an IntelliFlo, it uses named alarms rather than numbers: see our Pentair IntelliFlo alarm guide.

Safety first

Everything here is done at the breaker, the keypad, or the outside of the pump. Pentair warns never to open the inside of the drive or motor enclosure, because a capacitor bank inside holds a 230 VAC charge even when there is no power to the unit (SuperFlo VS manual, p. i). The pump must be on a circuit protected by a GFCI. If the GFCI trips without its test button being pressed, Pentair says not to use the pump until a qualified service representative has corrected the problem (p. i). If the breaker keeps tripping, leave it off and call.

Step one for any code: a full power cycle

Pentair's first instruction for any fault is the same: disconnect power to the pump, wait until all the keypad lights have gone out, then reconnect it. If the code comes back after that, the pump needs troubleshooting (SuperFlo VS manual, p. 19). Turning it off at the keypad isn't enough; use the breaker.

The fault codes

From the manual's alarms and fault codes table (SuperFlo VS manual, p. 19):

Code	Pentair's description	What to do
21	Communication link between the keypad (HMI) and the motor control has been lost	Power cycle. If it returns, Pentair's fix is to remove the drive's top cover and check the cable and 5-pin connector behind it. That's for a technician
1A	Power module over-current detected	Power cycle. If it keeps coming back, see "Over-current" below
17	Phase current offset out of range	Internal error: power cycle; if it won't clear, the drive may need service
1B	Phase current imbalance detected	Power cycle; if it returns, the drive needs diagnosis
0F	AC under-voltage: supply voltage below the operating range	Often clears itself. If not, the supply or the wiring
02	Phase current limit exceeded	See "Over-current" below
08	Diode bridge temperature limit exceeded	Internal error (temperature): check the motor fan cover, then power cycle
04	Power module temperature limit exceeded	As 08
06	Power factor correction (PFC) temperature limit exceeded	As 08
09	DC bus over-voltage detected	Internal error: power cycle; if it won't clear, the drive may need service
0A	DC bus under-voltage detected	As 09

Pentair's manual doesn't line up perfectly with itself here. The table gives 1A as the power module over-current and 02 as the phase current limit, while the paragraph above it describes 02 as the power module over-current. Its list of internal errors also includes a 16, which isn't in the table. Treat 02 and 1A as the same family: current, and possibly a pump that's hard to turn.

What the codes mean in practice

21: the keypad has lost the motor. The display and the drive electronics talk over a short cable with a 5-pin connector. Pentair's remedy is to remove the drive's top cover and check that the connector is plugged in and the cable isn't damaged (p. 19). With the drive's warning about stored charge, that's work for a technician.

02 and 1A: over-current. The drive is seeing more current than it should. Pentair says that if the error shows multiple times, there may be a problem with the pump's rotating assembly, and the next step is to take the pump apart and inspect the impeller and shaft seal (p. 19). Its troubleshooting chart lists a locked motor for a pump that won't start, with the fix being to disassemble the pump and try to turn the motor shaft by hand to free any blockage, and a damaged motor shaft as a reason to replace the pump (p. 18).

0F: low voltage. The supply has dropped below about 99 volts. Pentair says this can be normal voltage variation and will clear itself, and that otherwise there may be excess voltage drop from improper installation or the wrong supply voltage (p. 19). A 0F that keeps coming back is an electrical question about the circuit, not the pump.

08, 04 and 06: the drive is too hot. These are temperature limits inside the drive. Pentair's troubleshooting chart, for a pump that runs and then stops on an over-temperature or over-current fault, says to make sure the motor fan cover at the rear of the motor is free of dirt and debris, cleaned with compressed air, and notes the pump will restart by itself after one minute (p. 18). Turn the breaker off before cleaning around it.

17, 09 and 0A: internal errors. Pentair groups these, with the temperature codes, as errors from the drive's own self-diagnostic safety software. If they don't clear after several restarts, it says to cut power at the breaker until the keypad lights go out, and if the error still comes back, the drive may need service (p. 19). Pentair gives no separate remedy for 1B, phase current imbalance; the same power cycle is the first step, and a 1B that returns needs diagnosing.

Problems that don't show a code

Not priming. Pentair's chart lists air in the suction line or pump, not enough water, a dirty strainer basket and a damaged strainer pot o-ring. Check the lid is sealing and its o-ring is in place, and that the pool water is up to the skimmer (p. 18). The water level should be halfway up the skimmer opening; below it, the pump draws air and can run dry, which damages the shaft seal (p. 17). See pool pump losing prime.
Running at full speed for a few minutes when it starts. That's normal. The pump ships with priming enabled, and by default it runs at 3,450 RPM for five minutes every time it starts from a stop, except during a Quick Clean (p. 11).
Running but no flow. Pentair lists a loose impeller, air in the suction line, or a clogged line, partly closed valve or dirty filter (p. 19). See pump running but no water flow.
Running at times you didn't set. Until a custom schedule is programmed, the pump runs Pentair's default: 3,000 RPM from 8 a.m. for two hours, then 1,400 RPM for ten hours, then 2,200 RPM for two hours, then off until the next morning. The clock survives an outage of up to 24 hours; after a longer one it blinks until it's reset (p. 8).
Won't start at all, no code. Pentair's list starts with the supply: replace the fuse, reset the breaker or GFCI (p. 18). See pool pump not turning on.

When to call

Call when a code comes back after a full power cycle at the breaker, when 02 or 1A keeps returning (that means taking the pump apart), when 0F won't clear, or when any of the internal errors persist. Our variable-speed pump diagnostic reads the code against Pentair's manual, checks the supply voltage, the rotating assembly and the drive, and tells you what has failed and what putting it right involves before anything is quoted. Whether it's worth repairing or replacing is covered in repair or replace your pool pump.

If you don't know what's wrong, a diagnostic is $120, and it's credited toward your repair if you go ahead. Start from variable-speed pump repair, or answer a few questions in the Pool Problem Finder. A photo of the code and the pump's label helps.

Sources

Every manufacturer statement above links to this source. Page numbers are the printed page numbers in the manual.

Pentair, SuperFlo VST, SuperFlo VS and SuperMax VS Variable Speed Pumps Installation and User's Guide, P/N 356292 Rev. A (7/10/20).

Pentair, SuperFlo and IntelliFlo are trademarks of Pentair. Sta-Rite and SuperMax are trademarks of Pentair. They are named here only to identify equipment.

Pentair SuperFlo VS fault codes: what 21, 1A, 0F and the rest mean