Parker FL20 Servo Drive Fault Codes

Troubleshoot your Parker FL20 servo drive with our updated fault code list. Learn to interpret “Er” display codes, use FL Configurator software, and resolve servo trips.

Parker FL20 Fault Codes Reference Table

Below is the complete list of error codes and troubleshooting actions. Please refer to the specific “Er” code flashing on your servo drive’s LED display.

FL20-S Series Servo Drive Alarms

Fault Code and Meaning	Cause and Remedy
AL-01 Overcurrent	Cause: Main circuit wiring error, output short-circuit, internal short-circuit, interference, or damaged servo drive. Remedy: Check the wiring. Check if cable is short-circuited; fix or exchange it. Fix or exchange servo drive. Adopt anti-interference methods, improve wiring, etc.
AL-02 Overvoltage	Cause: Input voltage is too high or load rotary inertia is too large. Remedy: Check input voltage. Prolong deceleration time. Add external braking resistor. Reduce load or increase drive capacity.
AL-03 Undervoltage	Cause: Input voltage is low. Remedy: Check input voltage. Check whether main circuit is powered on.
AL-04 Hardware fault	Cause: Hardware fault. Remedy: Contact with Parker.
AL-05 Electric angle recognition error	Cause: Motor line sequence error. Remedy: Adjust line sequences, exchange two of them.
AL-06 Overload	Cause: Servo motor or encoder wiring is bad, mechanical factors, electromagnetic brake not released, or heavy load. Remedy: Check the wiring of servo motor and encoder. Check the transmission ratio of mechanical equipments. Check the wiring of electromagnetic brake. Reduce load or increase capacity of drive.
AL-07 Overspeed	Cause: Servo motor rotary speed is higher than max speed. Remedy: Check servo motor wiring and encoder wiring. Check for mechanical fault.
AL-09 Large position control error	Cause: Connection error (U, V, W or encoder), low Servo Drive gain, or position pulse frequency is too high. Remedy: Improve connection. Increase gain, adjust gain of speed and position. Reduce pulse frequency or adjust electronic gear.
AL-10 Encoder fault	Cause: Disconnected encoder, locked-rotor, or Servo motor fault. Remedy: Check encoder connection. Power on again; if alarm still occurs, please contact with Parker.
AL-11 Emergency stop	Cause: Logic of ESP input terminal not corresponding to connection, or hardware damage of ESP input. Remedy: Check connection or modify terminal logic. Set the function to other input terminal or contact with Parker.
AL-12 Servo drive overheat	Cause: Environment temperature too high, dirty radiator, foreign matter in fan, or fan damage. Remedy: Improve ventilation. Clean air outlet and cooling radiator. Clear fan of foreign matter. Exchange fan.
AL-13 Input phase loss	Cause: Phase loss with input phase or use of single-phase power supply. Remedy: Check input power supply. Check parameter setting.
AL-14 Regenerative braking error	Cause: Wrong braking resistor parameter or continuous brake time is too long. Remedy: Change parameter. Check load, servo only can drive non-potential energy load.
AL-16 Repeat setting of input terminal	Cause: Repeat setting of input terminal. Remedy: Reset input terminal.
AL-17 Disconnected encoder cable	Cause: Disconnected encoder cable. Remedy: Check for disconnected or damaged encoder cable.
AL-18 Rotary inertia recognition fault	Cause: Rotary inertia recognition fault. Remedy: Turn up Po013 manually.
AL-19 Alarm of encoder battery	Cause: Alarm of encoder battery. Remedy: Check if encoder cable is connected well. Check if battery level is 3.6V (if lower than 3.2V, keep control power at "ON"). Shield AL-19: So-38=1, So-43=1 reset alarm. Check if connection of battery is reliable.
AL-20 Uninitialized E2ROM	Cause: Uninitialized E2ROM of servo motor. Remedy: Servo motor encoder is not initialized; please study motor angle manually.
AL-21 Large zero drift	Cause: Servo drive zero drift is too large. Remedy: Check wiring or parameter setting.
AL-22 Z signal lost	Cause: Z signal is not detected after encoder rotates 3 times continuously. Remedy: Check encoder and Z signal cable.
AL-24 Encoder battery undervoltage	Cause: Encoder battery undervoltage. Remedy: If battery is undervoltage, reset mechanical origin to eliminate. Shield AL-24: So-48=1, So-41=1 (set current position as mechanical origin), So-43=1 reset alarm. PC/PLC will reset the mechanical origin.
AL-25 Motor overheat	Cause: Motor temperature is too high. Remedy: Improve ventilation.
AL-26 Temperature detection circuit disconnected	Cause: Temperature detection circuit is disconnected. Remedy: Check the cable.
AL-27 Overtravel	Cause: Overtravel alarm. Remedy: Setting range of FWD/FEV for overtravel protection again.
AL-28 E2ROM error	Cause: E2ROM error. Remedy: Contact with Parker.
AL-29 Ground protection	Cause: Ground protection. Remedy: Check for electric leakage of drive power port or servo motor output port.
AL-30 Motor locked-rotor protection	Cause: Motor locked-rotor. Remedy: Check if mechanical structure is blocked. Check if power cable is loosen. Check if load is too heavy (exceeding torque). Check if motor power cable is wired wrong.
AL-31 Large mixed error of full closed-loop	Cause: Parameters not set properly, transmission part not fastened, connection errors, low drive gain, or pulse frequency too high. Remedy: Check Po377, Po378 and Po380. Check the transmission part. Check connection of servo motor, encoder, and mechanical terminal. Increase gain, adjust gain of speed and position. Reduce pulse frequency or adjust electronic gear.
AL-32 Synchronism error of gate bridge	Cause: Parameters not set, transmission not fastened, or wrong pulse received. Remedy: Check Po383, Po384 and Po386. Check the transmission part. Check if the wiring of servo drive is correct and PC/PLC send correct command.
AL-33 Electric cam error	Cause: Electric cam data error. Remedy: Check whether electric cam data is correct.
AL-34 PLC command error	Cause: PLC command error. Remedy: Check whether PLC command is correct.
AL-35 Home searching overtime	Cause: Home searching overtime. Remedy: Check the wiring. Check the servo drive.
AL-36 Parameter copy error	Cause: Parameter copy error. Remedy: Check the wiring. Check the parameter setting.
AL-41 High-impedance state not detected	Cause: High-impedance state output is not detected after 8-core encoder is powered on. Remedy: Check 8-core encoder. Contact with Parker.

 

How to Read Parker FL20 Faults via FL Configurator

While the onboard LED display is useful for quick identification, connecting your PC to the drive using the FL Configurator software provides the most accurate diagnostic data for 2026. This software allows you to look deeper into the drive’s status signals at the exact moment of the trip.

Key Diagnostic Features:

• Fault Log: The FL20 stores a history of the last 10 fault events. Using the software, you can view these events along with the drive’s operating status (speed, current, bus voltage) at the time the error occurred.
• Real-Time Monitoring: You can monitor encoder feedback, I/O status, and torque command levels. This is essential for diagnosing “Er.011” (Overload) or “Er.015” (Encoder Error) faults that may be caused by mechanical binding or cabling issues.
• Waveform Trace: The FL Configurator features a digital oscilloscope function. You can trigger a trace on a fault bit to capture the current and velocity spikes that lead to an instantaneous trip.

Frequently Asked Questions (FAQ)

Q: What is the difference between a Warning and an Error code?

A:

• Warnings (AL): These indicate a condition is nearing a limit (such as regenerative power overload) but the drive remains enabled.
• Errors (Er): These are hard faults that immediately disable the PWM output, cause the motor to stop, and usually trigger the “Fault Out” digital output signal.

Q: How do I reset a Parker FL20 fault?

A: Once you have resolved the root cause, you can reset the drive by:

1. Toggling the Alarm Reset (A-CLR) digital input.
2. Using the “Fault Reset” button within the FL Configurator software.
3. Cycling the control power (L1C, L2C) off and back on.

Q: Why is my drive showing “Er.010” (Overcurrent)?

A: This is often caused by a short circuit in the motor power cable, a failure in the motor insulation, or a sudden mechanical jam. Check the U/V/W wiring for continuity to ground before attempting to restart the drive.

Q: Where can I find the fault history on the drive unit?

A: You can access the fault history directly via the keypad by navigating to the Auxiliary Function (AF) mode and selecting parameter AF_00. This will display the last 10 error codes stored in the drive memory.