PowerFlex 400 Fault Codes: F4, F5, F12, F13, F33, F81

Q: How do I clear a fault on a PowerFlex 400?

After correcting the cause: press Stop if P037 is 0…3, cycle power, set A197 to 1 or 2, or cycle a digital input set to 10 "Clear Fault" (p. 95). A reset can restart the machine at once, so follow the plant's lockout/tagout rules.

PowerFlex 400 (Bulletin 22C) fault codes: meaning, Type 1 or Type 2 and what to check; how to read the fault history, clear faults, set auto restart and handle a drive that will not run — from Rockwell 22C-UM001K.

Where the fault shows and how to read it

The PowerFlex 400 (Bulletin 22C) is the drive for fan and pump applications. A fault stops the drive. The keypad LCD flashes the fault number and the "Fault status" LED flashes red (22C-UM001K pp. 38, 95). Press Esc to acknowledge the fault and regain the keypad, then view b007 [Fault 1 Code], the most recent fault (p. 95).

Record before clearing (pp. 85–91):

d307…d309: the last three faults, d307 the most recent; a repeated fault is recorded once. From FRN 6.xx, d330…d336 hold faults 4 to 10.
d324…d327: output frequency, current, DC bus volts and drive status at the last fault.

A PLC on Modbus RTU reads the fault with Function Code 03 at register 8449 (Drive Error Codes); the value is the fault number in decimal, 0 = "No Fault" (pp. 146–147).

Type 1, Type 2 and clearing

From p. 95:

Type 1 "Auto-Reset/Run": if A163 [Auto Rstrt Tries] is above 0, the drive tries to reset after the A164 [Auto Rstrt Delay] timer; if the cause has gone, it restarts.
Type 2 "Non-Resettable": may need drive or motor repair, or comes from wiring or programming errors; correct the cause before clearing.

Manual clearing (p. 95):

Press Esc to acknowledge; view b007.
Correct the cause.
Clear by one of these:
Press Stop, if P037 [Stop Mode] is 0…3 (the "CF" options, where Stop clears the active fault, p. 51).
Cycle drive power.
Set A197 [Fault Clear] to 1 "Reset Fault" or 2 "Clear Buffer". Stop the drive first; it is mainly for clearing over a network (p. 78).
Cycle a digital input with T051…T054 = 10 "Clear Fault"; T053 (I/O Terminal 07) defaults to 10 (p. 53).

Automatic clearing (pp. 71, 96):

A163 ≠ 0 and A164 ≠ 0: clears a Type 1 fault and restarts. A163 ranges 0…9, default 0; A164 defaults to 1.0 s.
A163 ≠ 0 and A164 = 0: clears OverVoltage, UnderVoltage or Heatsink OvrTmp without restarting.

Safety: Auto Restart makes the drive issue its own start command (p. 96). With P036 [Start Source] = 3 "2-W Lvl Sens" (default) or 6 "2-W Lvl/Enbl" and Run held, the drive runs again after a fault clear without toggling Run (p. 50). Follow the plant's permit-to-work and lockout/tagout rules before any reset.

Fault code tables

Paraphrased from Table 26, pp. 96–97. "—" = the table prints no type.

Supply and DC bus

Code	Name	Type	Meaning	Check
F3	Power Loss	2	FRN 5.03 and earlier only: DC bus below undervoltage within 200 ms of a start, excessive ripple, or input phase loss	As F4
F4	UnderVoltage	1	DC bus below minimum	Line voltage dips, outages; input fuses
F5	OverVoltage	1	DC bus above maximum	High line or transients; motor regeneration: longer decel or a dynamic brake chopper
F17	Input Phase Loss	2	FRN 6.xx and later: excessive DC bus ripple, see `d329` [DC Bus Ripple V]	Missing phase, blown fuse; deliberate single-phase supply needs derating to 35 %

Current, overload, temperature

Code	Name	Type	Meaning	Check
F6	Motor Stalled	1	Cannot accelerate or decelerate the motor	Increase `P039`…`A147` [Accel Time x] or reduce load so current stays within `A179` [Current Limit 1]
F7	Motor Overload	1	Internal electronic overload trip	Motor load against `P033` [Motor OL Current]; `A170` [Boost Select]
F8	Heatsink OvrTmp	1	Heatsink over a predefined temperature	Blocked or dirty fins; ambient max 45 °C (IP30/NEMA 1/UL Type 1) or 50 °C (IP20/Open); fan
F12	HW OverCurrent	2	Output current above the hardware limit	Programming; excess load; `A170`; DC brake volts too high
F63	SW OverCurrent	1	`A183` [SW Current Trip] exceeded	Load requirements and `A183`
F64	Drive Overload	2	Drive rating of 110 % for 1 min or 150 % for 3 s exceeded	Reduce load or extend accel time
F32	Fan Fdbck Loss	2	FRN 6.xx and later, frames E and F only: cooling fan feedback lost	Fans clear of debris and spinning; replace if needed

A183 is a software instantaneous trip (within 100 ms), default 0.0 = disabled (p. 76).

Ground faults, shorts, load loss

Code	Name	Type	Meaning	Check
F13	Ground Fault	2	Current path to ground at one or more output terminals	Motor and output wiring
F38 / F39 / F40	Phase U / V / W to Gnd	2	Phase-to-ground fault between drive and motor	Drive–motor wiring; motor; replace drive if it cannot be cleared
F41 / F42 / F43	Phase UV / UW / VW Short	2	Excessive current between two outputs	Output wiring and motor for a short; replace drive if it cannot be cleared
F15	Load Loss	1	Output current below `A184` [Load Loss Level]	Lost load, e.g. a broken belt

A184 and A185 [Load Loss Time] are disabled by default (p. 76).

Control signals, analog, communications

Code	Name	Type	Meaning	Check
F2	Auxiliary Input	1	Auxiliary input interlock open	Remote wiring; communications program faulting on purpose
F29	Analog Input Loss	1	Input set to fault on signal loss has lost its signal	`T072`/`T076`; loose or broken input wiring
F94	Function Loss	2	`P036` = 6 and terminal 01 opened	Close terminal 01 and restart
F71	Net Loss	—	Communication network faulted	Cycle power; cabling; adapter settings; external network
F81	Comm Loss	2	RS-485 (DSI) port stopped communicating	RS-485 wiring; adapter or HIM unplugged; raise `C106`; change `C105` if suitable

F2: an input set to 9 "Aux Fault" that is not active faults the drive at once (p. 53).
F29: loss means below 1 V or 2 mA; normal resumes at ≥ 1.5 V or 3 mA. T072 [Analog In 1 Loss] = 1 "Fault (F29)" makes it fault (p. 59).
F81: C105 [Comm Loss Action] defaults to 0 "Fault" — F81 and coast to stop; C106 [Comm Loss Time] defaults to 5.0 s, range 0.1…60.0 s (p. 66). For intermittent faults, check the whole industrial network.

System and hardware

Code	Name	Type	Meaning	Check
F33	Auto Rstrt Tries	2	Reset-and-run failed for the `A163` count	Fix the original cause, clear manually
F48	Params Defaulted	—	Drive commanded to write defaults to EEPROM	Clear the fault or cycle power; reprogram
F100	Parameter Checksum	2	Board checksum does not match the calculated one	`P041` [Reset To Defalts] = 1
F70	Power Unit	2	Power section failure	Cycle power; replace drive if it cannot be cleared
F122	I/O Board Fail	2	Control and I/O section failure	Cycle power; replace drive if it cannot be cleared

P041 = 1 "Factory Rset" restores factory defaults and causes F48. Packaged fan and pump drives ship with custom defaults that differ from factory defaults, so some parameters must be re-entered; the manual points to 23C-IN001 (p. 52).

Drive will not run, no fault

From the symptom tables, pp. 98–99:

No output voltage: supply, fuses, disconnects, motor wiring; a Start signal (2-wire: Run Forward or Run Reverse, not both); I/O Terminal 01 active; P036 matches the setup; A166 [Reverse Disable].
No start from the keypad: green LED above Start off — set P036 = 0 "Keypad"; check the Stop input at I/O Terminal 01.
"Run" lit, 0 Hz: check d301 [Control Source], b002 [Commanded Freq] and P038 [Speed Reference]; meter an analog reference.
No power-up: supply, fuses; the P2–P1 jumper or DC bus inductor.

When it is hardware

The table points to replacing the drive only when F38–F43, F70 or F122 cannot be cleared, and the fan for F32 (pp. 96–97).

Before calling Rockwell or an authorized repair provider, record: catalog number, firmware d320 [Control SW Ver] (p. 87) — F3, F17 and F32 depend on FRN; the fault history; what the machine was doing. For the PowerFlex 525, see PowerFlex 525 fault codes. Need an engineer on site: request support.

Frequently asked questions

What is fault F4 UnderVoltage on a PowerFlex 400?

F4 means the DC bus voltage fell below its minimum; it is a Type 1 fault (22C-UM001K p. 96). Watch for low line voltage or outages and check the input fuses.

What is fault F81 Comm Loss on a PowerFlex 400?

F81 means the RS-485 (DSI) port stopped communicating; it is a Type 2 fault (p. 97). The response is set in C105, default 0 "Fault", and the wait time in C106, default 5.0 s (p. 66).

What is fault F33 Auto Rstrt Tries?

F33 means the drive tried to reset and resume running for the number of tries in A163 without success; it is a Type 2 fault (p. 97). Fix the original fault, then clear manually.

How do I clear a fault on a PowerFlex 400?

After correcting the cause: press Stop if P037 is 0…3, cycle power, set A197 to 1 or 2, or cycle a digital input set to 10 "Clear Fault" (p. 95). A reset can restart the machine at once, so follow the plant's lockout/tagout rules.

Sources

Rockwell Automation, 22C-UM001K-EN-E, PowerFlex 400 Adjustable Frequency AC Drive for Fan and Pump Applications User Manual, 09/2025 — chapter 4 pp. 95–99; parameters pp. 50–53, 59, 66, 71, 76, 78, 85–91; pp. 38, 146–147

Read 8 November 2026. This article paraphrases the sources and does not quote them; read the original documents before designing or working on a system.