Parker AC20F Drive Fault Codes

Troubleshoot your Parker AC20F Fluid/Pump drive with our updated fault code list. Learn to interpret Trip messages, use DSE Lite for PID diagnostics, and minimize downtime.

Parker AC20F Fault Codes Reference Table

Below is the complete list of trip messages and warning codes. Please refer to the specific Trip Message displayed on your keypad or HMI.

AC20F Series - Trips, Warnings & Alerts

Fault Code and Meaning	Cause and Remedy
1 Over Voltage	Cause: The drive internal DC link voltage is too high. The supply voltage is too high. Trying to decelerate a large inertia load too quickly (DECEL TIME too short). The brake resistor is open circuit. Remedy: Enable the DC Link Volts Limit feature. Check supply voltage. Increase deceleration time. Check braking resistor connection.
2 Stack Over I	Cause: The motor current exceeded the capabilities of the power stack. Instantaneous overcurrent detected by the power stack. Remedy: Refer to 'Over Current' (Fault ID 4) entries for detailed troubleshooting.
3 Under Voltage	Cause: DC link low trip. Supply is too low. Power down occurred. Remedy: Check incoming power supply voltage. Check for loose power connections.
4 Over Current	Cause: The motor current being drawn from the drive is too high. Trying to accelerate a large inertia load too quickly (ACCEL TIME too short). Trying to decelerate a large inertia load too quickly (DECEL TIME too short). Application of shock load to motor. Short circuit between motor phases. Short circuit between motor phase and earth. Motor output cables too long or too many parallel motors. FIXED BOOST level set too high. Remedy: Increase acceleration or deceleration times. Check for short circuits in motor or cabling. Check motor cable length. Reduce FIXED BOOST setting. Remove mechanical shock loads.
5 Current Lim	Cause: (V/Hz mode only) Current exceeded 200% of stack rated current for 1 second. Caused by shock loads. Remedy: Check for mechanical binding or shock loads. Review system sizing.
6 Motor Stall	Cause: The motor has stalled (not rotating). Drive in current limit >200 seconds. Motor loading too great. FIXED BOOST level set too high. Remedy: Reduce motor load. Adjust FIXED BOOST level.
7 Inverse Time	Cause: A prolonged overload condition, exceeding the Inverse Time allowance. Remedy: Remove the overload condition.
8 Motor I2t	Cause: (PMAC Motor only) Prolonged load condition exceeding motor rated current. Estimated motor load has reached 105%. Remedy: Reduce load on the motor. Check motor rating configuration.
9 Low Speed I	Cause: Motor drawing too much current (>100%) at zero output frequency. FIXED BOOST level set too high. Remedy: Reduce FIXED BOOST parameter.
10 Heatsink Temp	Cause: Drive heatsink temperature too high. Ambient air temperature is too high. Poor ventilation or spacing between drives. Remedy: Check heatsink fan is rotating. Improve cabinet ventilation. Check spacing requirements.
11 Internal Temp	Cause: Processor or ambient temperature within power stage too high. Ambient temperature in the drive is too high. Remedy: Check cooling and ambient temperature surrounding the drive.
12 Motor Temp	Cause: The motor temperature is too high. Excessive load. Motor voltage rating incorrect. FIXED BOOST level set too high. Prolonged operation at low speed without forced cooling. Break in motor thermistor connection. No link fitted to thermistor terminals. Remedy: Check motor loading and cooling. Check thermistor connections and links. Verify motor parameters.
13 Dynamic Brake	Cause: External dynamic brake resistor has been overloaded. Trying to decelerate a large inertia too quickly or too often. Remedy: Increase deceleration time. Reduce frequency of braking. Check brake resistor sizing.
14 Digout Load	Cause: 24V output voltage dropped by Digital output overload > 50 mA. Remedy: Connect 24V user supply voltage. Decrease output load.
15 Anin 1 Over	Cause: Analog Input current > 30 mA (Overload detected only in Current Mode). Remedy: Check wiring to Analog Input 1. Check source signal level.
16 Anin 2 Over	Cause: Analog Input current > 30 mA (Overload detected only in Current Mode). Remedy: Check wiring to Analog Input 2. Check source signal level.
17 Contactor	Cause: DC Link failed to reach undervoltage trip level within contactor feedback time. The Line contactor failed to connect. Missing 3-phase line supply. Remedy: Check line contactor. Check 3-phase supply.
18 Phase Fail	Cause: Indicates a missing input phase. Remedy: Check incoming power supply lines. Check fuses/breakers.
19 Output Phase	Cause: Motor Output Phase is missing. Motor Phase not connected. Current sensor missing or not correctly connected. Remedy: Check motor connections. Check current sensor connections.
20 Vdc Ripple	Cause: The DC link ripple voltage is too high. Missing input phase. Repetitive start/stop or forward reverse action. Remedy: Check for missing input phase. Reduce frequency of start/stop cycles.
21 Pwr Loss Stop	Cause: A Power Loss Ride Through sequence occurred and limits were exceeded. '0315 Pwrl Time Limit' exceeded. Motor speed reached zero during sequence. Remedy: Check power supply stability. Adjust Power Loss Ride Through parameters.
22 Overspeed	Cause: Motor Speed >150% base speed when in Sensorless Vector mode. Remedy: Check motor parameters. Check speed control loop tuning.
23 PMAC Speed	Cause: (PMAC Motor) Start feature in Sensorless Vector Control failed. Speed hasn't reached setpoint after 5 seconds to move to closed loop. Remedy: Check motor load during start. Check sensorless vector parameters.
24 Speed Sensor	Cause: Switchover Enable P0256 = TRUE. Control Type set directly to sensorless mode. Remedy: Check encoder feedback. Verify switchover parameters.
25 Speed Error	Cause: Difference between actual motor speed and speed setpoint is too large. Greater than threshold for a period of time. Remedy: Check PID loop tuning. Check for mechanical binding.
26 Feedback Err	Cause: Configuration error for Closed Loop Vector control. Pulse Encoder IO Option not correctly configured. Remedy: Configure Pulse Encoder IO Option correctly.
27 Command Loss	Cause: Communication lost. Connection to Remote Keypad lost. Remedy: Check keypad cable.
28 Comms Break	Cause: Lost option communications. Break in option communications detected. Remedy: Refer to option communications manual.
29 Base Modbus	Cause: Lost Base Modbus communications. Remedy: Check Modbus cabling. Check Modbus master status.
30 Fieldbus	Cause: Loss of connection to fieldbus master. Cable disconnected. Master offline. EMC problems. Remedy: Check cable to fieldbus master. Check state of fieldbus master. Check for EMC interference.
31 STO Active	Cause: Attempt to run the motor with Safe Torque Off active. STO wiring issues. Maximum 50mA current allowance on 24V output exceeded. Remedy: Check the STO wiring. Power the drive off and on to clear. Check 24V output load.
32 External Trip	Cause: The external (application) trip input is high. Remedy: Refer to the application description to identify the source of the signal.
33 - 36 Application Trip (A1 - A4)	Cause: Controlled by Application_Trips block in configuration. Remedy: Check application specific logic.
37 CPU Loading	Cause: Combination of high switching frequency, network traffic, and complicated configuration. Remedy: Reduce the Ethernet load. Reduce the switching frequency.
38 Track Error p	Cause: Difference between actual pressure and demand is too high. Remedy: Optimize controller adjustment. Increase P ERROR WINDOW. Increase P ERROR TIME.
39 Track Error q	Cause: Difference between actual volume flow and demand is too high. Remedy: Optimize controller adjustment. Optimize speed limits. Increase Q ERROR WINDOW. Increase Q ERROR TIME.
40 Comp Protect	Cause: Actual motor speed lower than minimal pump/motor speed for protection time. Remedy: Switch DCP off if no pressure/flow needed. Increase COMP PROTECTION time.
41 p max	Cause: The actual pressure is greater than the maximal pressure value. Remedy: Check pressure regulation. Check maximal pressure settings.
42 Track Error Vel	Cause: (PMAC with feedback) Speed deviation > 500 rpm for > 1 second. Remedy: Check motor feedback alignment. Check load stability.
25 (Autotune) ALL_TESTS_DISABLED	Cause: Parameter 0038 ATN TEST DISABLE set to 31. Remedy: Adjust parameter 0038 settings.
27 (Autotune) LEAKAGE_L_TIMEOUT	Cause: Required current cannot be reached. Remedy: Check motor connections and supply. Retry autotune.
28 (Autotune) MOTOR_STALLED_ERROR	Cause: Motor stall during autotune (not rotating). Remedy: Check for mechanical blockage. Uncouple motor from load if necessary.
34 (Autotune) SUPPLY_VOLTS_LOW	Cause: Available voltage supply is less than 70% of the rated motor volts. Remedy: Check incoming power supply. Verify motor voltage rating.

 

How to Read Parker AC20F Faults via DSE Lite

While the keypad provides immediate feedback, connecting your PC to the drive using the Parker Drive System Explorer Lite (DSE Lite) software yields the most accurate diagnostic data for 2026. This is particularly important for the AC20F, as faults are often related to external sensor feedback (pressure/flow transducers).

Key Diagnostic Features:

• Trips History: Access the “Trips History” parameter to view the last 10 events. This is crucial for identifying “nuisance trips” caused by hydraulic pressure spikes or air in the lines.
• PID Loop Monitoring: Since the AC20F is often used for pump control, use DSE Lite to monitor the PID Feedback and PID Error signals. A trip indicating “Sensor Loss” or “Feedback Error” can be visualized here to see if the 4-20mA signal dropped out before the fault.
• Oscilloscope Function: Trigger the software scope on “Output Current” or “DC Bus Voltage.” This helps distinguish between a true mechanical jam (pump blockage) and an electrical issue.

Frequently Asked Questions (FAQ)

Q: What is the difference between a Warning and a Trip?

A:

• Warnings: These alert you to a developing issue (e.g., “High Pressure Warning” or “Motor Temp”) but allow the pump/fan to continue running.
• Trips: These indicate a critical failure (e.g., “OVER CURRENT” or “STO TRIPPED”) that immediately stops the motor to prevent damage to the drive or the hydraulic system.

Q: How do I reset a Parker AC20F fault?

A: Once the root cause is addressed, you can reset the trip via:

1. Pressing the STOP/RESET button on the keypad.
2. Toggling a specific Digital Input configured for “Remote Reset.”
3. Sending a reset command via the Fieldbus interface (Profinet/EtherNet/IP).

Q: Why am I getting a “Feedback Loss” trip?

A: On AC20F units running in PID mode, this trip occurs if the transducer signal (usually 4-20mA or 0-10V) falls below a set threshold (e.g., wire break). Check your sensor wiring and ensure the 24V supply to the sensor is active.