Pentair WhisperFlo VST Temperature & Internal Faults
Several WhisperFlo VST fault codes are triggered by UL 60730 self-diagnostic safety software or temperature protection circuits in the drive. These faults include temperature limits (04, 06, 08), DC bus voltage faults (09, 0A), and current-related faults (17, 16, 02).
The manual groups these together: faults 1A, 17, 16, 02, 08, 04, 06, 09, and 0A are described as "Internal Errors" that can occur based on operating conditions and required self-diagnostic safety software. The first step for all of them is a hard power cycle.
Fault Code Reference
| Fault Code | Description | Component |
|---|---|---|
| 04 | Power module temperature limit exceeded | Drive inverter section |
| 06 | Power Factor Correction (PFC) temperature limit exceeded | Drive PFC circuit |
| 08 | Diode bridge temperature limit exceeded | Drive rectifier |
| 09 | DC bus over voltage detected | Drive DC bus |
| 0A | DC bus under voltage detected | Drive DC bus |
| 17 | Phase current offset out of range | Drive current sensing |
| 16 | Phase current imbalance detected | Drive current sensing |
| 02 | Absolute phase current limit exceeded | Drive output stage / rotating assembly |
Note on fault 02: While the fault table lists 02 as "Absolute Phase Current Limit Exceeded," the manual also describes fault 02 in the context of rotating assembly problems (impeller and shaft seal issues). If fault 02 appears repeatedly, check the rotating assembly as described in the Fault 1A guide in addition to the drive troubleshooting steps below.
Step 1: Hard Power Cycle (All Faults)
- Turn off the circuit breaker to the pump
- Wait until all keypad LEDs have turned off — this ensures the capacitor bank has discharged (allow up to 60 seconds)
- Turn the breaker back on
- Restart the pump
- Monitor for recurrence — if the fault does not return, continue normal operation
The manual states that if these errors do not clear after multiple restart attempts, the drive should undergo a hard power cycle. If the error continues to appear after power is reconnected, the drive may need service.
Temperature Faults (04, 06, 08)
These faults mean a heat-sensitive component in the drive has exceeded its safe operating temperature.
Common Causes
- Poor ventilation: Equipment enclosure without airflow or pump in direct sun
- High ambient temperature: Equipment room temperature too high
- Debris blocking motor fan: Leaves, dust, or debris blocking airflow through the motor fins and fan guard
- Loose wiring connections: Resistance at terminals generates heat
- Low voltage: Higher current draw under low voltage increases heat in drive components
Troubleshooting
- Clean back of pump — use compressed air to remove debris from motor fins and fan guard
- Ensure the equipment area has adequate airflow — remove obstructions from around the motor
- If pump is in an enclosure, verify there is ventilation — do not seal it completely
- Check all wiring connections for tightness and corrosion
- Verify supply voltage is within range (see Fault 0F guide)
DC Bus Faults (09, 0A)
Fault 09 — DC Bus Over Voltage
The DC bus inside the drive has exceeded its maximum voltage. Causes include:
- High utility voltage spike
- Back-driving: water continuing to flow through the pump after it stops (thermosiphon from solar heating, elevated spa draining back)
- Nearby equipment causing voltage spikes on the line
Solution for back-driving: Install a check valve on the discharge side of the pump to prevent reverse flow when the pump stops.
Fault 0A — DC Bus Under Voltage
Usually linked to low supply voltage — refer to the Fault 0F troubleshooting guide for diagnosis steps.
Current Sensing Faults (17, 16, 02)
These faults are generated by the UL 60730 self-diagnostic software monitoring current sensing circuits:
- 17 (Phase current offset): Current sensing baseline is out of calibration range
- 16 (Phase current imbalance): Unequal current between motor phases — note the WhisperFlo VST uses fault code "16" where some other Pentair pumps use "ib"
- 02 (Phase current limit): Instantaneous current spike exceeded drive limits — also check for rotating assembly issues if recurring
These faults are often transient and clear after a power cycle. If recurring, they may indicate a motor winding issue, failing drive components, or (for fault 02) a mechanical problem with the impeller or shaft seal.
When the Drive Needs Replacement
If a fault from this group persists after:
- Multiple hard power cycles (disconnect at breaker until all LEDs go out, then reconnect)
- Verifying ventilation and wiring
- Confirming supply voltage is in range (99–251V)
- Checking rotating assembly if fault 02 is involved
...then the drive board itself may have failed and needs replacement or service.
Replacement Parts
| Part | Part Number |
|---|---|
| Drive Cover | 356279 |
| Drive Kit | 356282 |
| Motor | 356286s |
| Motor/Drive Assembly (complete) | 356289s |
Call Pentair Technical Service at (800) 831-7133 before ordering drive components — they can help confirm whether the drive or motor is at fault.