This article covers the PowerFlex 753 and the standard PowerFlex 755. Every code, parameter and page number comes from programming manual
Faults, alarms and configurable conditions
Per
- A major fault stops the drive (Not Ready). A minor fault does not stop a running drive, but must be cleared before it can run again.
- A Resettable Fault can be cleared once the cause is gone. A Non-Reset Fault normally needs drive or motor repair; the cause must be corrected first, and the fault resets on power-up after the repair. An Automatic Drive Reset fault makes the drive reset when it occurs.
- Alarm 1 (type 1): a condition exists; configurable. Alarm 2 (type 2): a configuration error, the drive cannot start; not configurable.
- Configurable: the parameter in the "Configuration Parameter" column selects the response: Ignore (0), Alarm (1), Flt Minor (2), FltCoastStop (3), Flt RampStop (4), Flt CL Stop (5), FltNonRest (6, cycle power to clear).
Flt Minor only works when P950 [Minor Flt Cfg] is enabled; otherwise it acts like a major fault (p. 309).
Reading the number: the prefix is the port
The HIM shows "Fault Code" with the fault text and the time elapsed since the fault was detected, in hh:mm:ss (p. 312). Codes come in three formats (p. 315):
| Port | Format | Example in the manual |
|---|---|---|
| 00 (host drive) | event number only | Fault Code 3 = "Power Loss" |
| 01…09 | PEEE | Fault Code 4001 = fault 1 "Analog In Loss" on an I/O module in port 4 |
| 10…14 | PPEEE | Fault Code 14037 = fault 37 "Net IO Timeout" on port 14 |
So "F4" or "fault 13" is Fault Code 4 or 13 on port 0. Modules in ports generate codes 3000…13999; for 13000…13999 the manual refers to
STS indicator
- Flashing red: major fault (P951). Steady red: non-resettable fault. Red/yellow alternating: minor fault.
- Steady yellow: type 1 alarm (P959 / P960). Flashing yellow: start inhibit on a 753 (P933 [Start Inhibits]), type 2 alarm on a 755 (P961 [Type 2 Alarms]) (pp. 310–311).
Common codes
Meaning and Check are TDL's paraphrase of the manual; "suggestion" marks points the manual does not make. Full list: Table 10, pp. 316–332.
| Code | Text | Type | Meaning | Check | p. |
|---|---|---|---|---|---|
| 2 | Auxiliary Input | Resettable | The input assigned in P157 [DI Aux Fault] is open | External interlock chain | 316 |
| 3 | Power Loss | Configurable, P449 (default Alarm) | DC bus below the power loss threshold for longer than the set time | Threshold = P12 [DC Bus Memory] − P451/P454; time P452/P455; suggestion: supply, voltage dips | 316, 102–103 |
| 4 | UnderVoltage | Configurable, P460 (default FltCoastStop) | P11 [DC Bus Volts] fell below P461 [UnderVltg Level] | Suggestion: P958 [Fault Bus Volts], input voltage, fuses | 316, 104 |
| 5 | OverVoltage | Resettable | DC bus exceeded its maximum | P11; suggestion: decel time, high-inertia load | 316 |
| 7 | Motor Overload | Configurable, P410 (default FltCoastStop) | Internal electronic motor overload tripped | P7 [Output Current], P26 [Motor NP Amps], P413, P414 | 316, 99 |
| 8 | Heatsink OvrTemp | Resettable | Heatsink above 100 %, tripping between 115…120 °C | P943 / P944; suggestion: fans, filters, enclosure temperature | 316 |
| 12, 36 | HW OverCurrent, SW OverCurrent | Resettable | Output current above the hardware limit (12), or above the 1 ms rating, typically 200…250 % of continuous rating (36) | 12: grounded motor/cable, load, programming; insulation-test the motor wiring (the manual gives no checks for 36) | 317, 319 |
| 13 | Ground Fault | Resettable | Current path to earth above 25 % of drive rating | As for code 12; insulation-test the motor wiring | 317 |
| 38…40, 41…43 | Phase U/V/W to Grnd, Phase UV/VW/WU Short | Resettable | Phase-to-ground fault between drive and motor, or excess current between two output terminals | Rotate U/T1, V/T2, W/T3: if the fault follows the wire, it is field wiring; if not, suspect the drive | 319 |
| 17 | Input Phase Loss | Configurable, P462 (default FltCoastStop) | DC bus ripple above the preset level | In this order: input impedance balance, P463, tune the bus or speed regulator | 317, 104 |
| 64 | Drive OverLoad | Alarm 1 / Resettable | P940 [Drive OL Count] above 50 % is the alarm, above 100 % the fault | Reduce the mechanical load | 320 |
| 33 | AuRsts Exhausted | Resettable | Auto restart tried P348 times without success | Suggestion: find the original fault in the fault queue | 319 |
| 81 | Port 1 DPI Loss | Resettable | The DPI port stopped communicating (suggestion: a HIM is usually on DPI port 1 or 2, p. 16) | Connections, drive grounding; the configuration column lists P324 [Logic Mask] | 321 |
| 224…228 | Port 4…8 Comm Loss | Configurable, P965 (default Fault) | The module in the port stopped talking to the main control board | Module seated and screwed down; network connections; delay P966 | 328, 105 |
| 203 | Port 13 Adapter | Resettable | Embedded EtherNet/IP adapter fault | Adapter event queue, e.g. 13031 Net Dup Address, 13035 Net Idle Fault, 13037 Net IO Timeout | 327, 352 |
| 211; 210, 212, 213 | Safety Brd Fault; jumper faults | Resettable | Safety option module fault (211); ENABLE or SAFETY jumper does not match whether a safety module is fitted (210, 212, 213) | ENABLE jumper; for Safe Torque Off |
327–328 |
| 91 | Pri VelFdbk Loss | Configurable (parameter on the feedback module) | Primary velocity feedback lost | Feedback module and its link to the main control board; open-wire detection (encoder module code xx000) needs differential signals | 321, 355 |
For the 755 embedded EtherNet/IP adapter, the response to lost I/O is set by port 13 P54 [Comm Flt Action], and to a controller in program mode or faulted by P55 [Idle Flt Action]; both default to Fault (p. 238). TDL's advice: do not change P54/P55 to Hold Last or Zero Data (their options are Fault, Stop, Zero Data, Hold Last, Send Flt Cfg), or set a configurable fault to Ignore, just to finish a shift; that takes the protection away.
Read the fault before clearing it
- On the HIM open Diagnostics and select Faults or Alarms for the history (p. 310). Marker 49 "Drive Powerup" shows a power cycle; 51 "Clr Fault Queue" shows the queue was cleared (p. 319).
- Read P951 [Last Fault Code]: the first fault since the last reset. A breakdown often produces a chain of faults, and knowing the first one usually helps find the cause (p. 166).
- Record the values captured at the fault: P954 / P955 [Status1/2 at Fault], P956 [Fault Frequency], P957 [Fault Amps], P958 [Fault Bus Volts], P962 / P963 [AlarmA/B at Fault] (pp. 167–171, 369). For some faults the captured value may not match the actual peak or low because of data latency.
- If a parameter is not visible, set P301 [Access Level] to "Advanced" or "Expert" (p. 315).
Clearing faults and auto restart
The manual's sequence (p. 312): press "Clear" to acknowledge, correct the cause, then clear the fault with the Stop key, by cycling power, or with "Clear" in the Faults menu of the Diagnostic folder. The fault will not clear while the cause remains.
Automatic options (pp. 89–90, 308):
- Auto Restart: only for faults with "Y" in the Auto Reset column, and only if the drive was running. With P348 [Auto Rstrt Tries] above 0 (0…9, default 0), after P349 [Auto Rstrt Delay] (default 1 s) the drive tries to reset; if the cause is gone, the fault resets and the drive restarts.
- Auto Clear: for faults while stopped, via P338 [AutoClrFlt Tries] and P339 [AutoClrFlt Delay]; the drive becomes ready but does not start.
- P347 [Auto Retry Fault] bit 0 enables fault F33 when the tries are used up; bit 1 enables F34 "AutClrFltExhaust".
Safety: resetting a fault, especially with Auto Restart enabled, can start the motor at once if a run command is still present. Clear the machine area and follow the plant's lockout and permit-to-work rules.
When it is hardware
- Steady red STS, or a Non-Reset Fault: this type normally needs drive or motor repair (pp. 308, 310).
- Board-level codes: 108 "Anlg Cal Chksum" (replace the main control board); 110 / 111 (check the ribbon cable between the main control board and the power interface board, then replace the power interface board) (p. 322).
- 900…927 (Automatic Drive Reset, except 917, which is Resettable on the 753): mostly check grounding or replace the main control board; some say contact technical support (pp. 331–332).
- 755 Frame 8 and larger: 10101 "I1 Comm Loss" (Non-Reset: the fiber-optic link between the fiber optic interface board and the power layer interface board is lost; also check the "Fiber Loss" segment on the PLI board
7-segment display); for 10110 "I1 Bus Overvolt", if the bus voltage in port 10, in port 11 and at the DC+/DC− test points disagree, the bus sensing boards may be damaged (pp. 313, 335–336). Frame 8 and larger part replacement follows service manual750-TG001 (p. 315).
TDL does not repair circuit boards. Module, board or drive replacement goes through Rockwell Automation or a Rockwell-authorised service provider. TDL can help isolate the fault, back up and reload parameters, and recheck afterwards. Replacement part numbers: PowerFlex 753/755 catalog. Moving to 755TS: see PowerFlex 755 to 755TS migration.
Before calling support
Rockwell asks for (p. 369): catalog number and series, serial number, firmware revision, the code in P951, installed options and their ports, plus P954…P958, P962 and P963. DriveExplorer and DriveExecutive include a Tech Support wizard that saves diagnostic data as a text file (p. 370).
For the smaller PowerFlex 525, see PowerFlex 525 fault codes. Need an engineer on site: request support.
Frequently asked questions
What is fault F4 on a PowerFlex 755?
Fault Code 4 is "UnderVoltage": P11 [DC Bus Volts] fell below P461 [UnderVltg Level]. It is a configurable fault; the response is set in P460 [UnderVltg Action], default FltCoastStop (
What is fault 13 on a PowerFlex 753?
Fault Code 13 is "Ground Fault": a current path to earth above 25 % of drive rating. Check the motor and output wiring and insulation-test the motor wiring (p. 317). For codes 38, 39 or 40, rotate U/T1, V/T2, W/T3: if the fault follows the wire it is field wiring, if not suspect the drive.
What do fault codes 4001 or 14037 mean on a PowerFlex 755?
The leading digits are the port number. Ports 01…09 use PEEE, so 4001 is fault 1 of the module in port 4. Ports 10…14 use PPEEE, so 14037 is fault 37 "Net IO Timeout" on port 14 (p. 315).
Where do I find the first fault on a PowerFlex 755?
P951 [Last Fault Code] holds the first fault since the last reset; the full history is under Diagnostics > Faults on the HIM. Values at the fault are in P954…P958, P962 and P963 (pp. 166–171, 310).
Why does a PowerFlex 755 show F33 AuRsts Exhausted?
The drive tried to reset the fault and resume running for the number of tries set in P348 [Auto Rstrt Tries], without success (p. 319). Find the original fault in the fault queue, fix it, then clear the fault.
Sources
- Rockwell Automation,
750-PM001Q-EN-P , PowerFlex750-Series AC Drives Programming Manual (firmware 1.015…20.003), 11/2024 — chapter 6 pp. 308–347, 352, 355, 369–370; chapter 1 p. 16; parameters pp. 89–90, 99, 102–105, 166–171, 238
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.