Danfoss VACON 20 Drive Fault Codes List

Access the complete reference guide for Danfoss VACON 20 drive fault codes. Learn to diagnose F-codes via VACON Live, troubleshoot PLC errors, and reset alarms.

VACON 20 Fault Codes Reference Table

VACON Frequency Converter Fault Codes

Fault Code and Meaning	Cause and Remedy
1 Overcurrent	Cause: Frequency converter has detected too high a current (>4*In) in the motor cable: sudden heavy load increase short circuit in motor cables unsuitable motor Remedy: Check loading. Check motor size. Check cables.
2 Overvoltage	Cause: The DC-link voltage has exceeded the internal safety limit: deceleration time is too short high overvoltage peaks in mains Remedy: Increase the deceleration time (Par.4.3 or Par.4.6).
3 Earth fault	Cause: Current measurement has detected extra leakage current at start: insulation failure in cables or motor Remedy: Check motor cables and motor.
8 System fault	Cause: component failure faulty operation Remedy: Reset the fault and restart. If the fault re-occurs, contact the distributor near to you. NOTE! If fault F8 occurs, find out the subcode of the fault from the Fault History menu under Id xxx!
9 Under voltage	Cause: The DC-link voltage has gone below the internal safety limit: most probable cause: supply voltage is too low frequency converter internal fault Power outages Remedy: In case of temporary supply voltage break reset the fault and restart the frequency converter. Check the supply voltage. If it is adequate, an internal failure has occurred. Contact the distributor near to you.
10 Input phase fault	Cause: Input phase is missing. Remedy: Check supply voltage, fuses and cable.
11 Output phase fault	Cause: Current measurement has detected that there is no current in one motor phase. Remedy: Check motor cable and motor.
13 Frequency converter under temperature	Cause: Heat sink temperature is under -10 °C. Remedy: Check the ambient temperature.
14 Frequency converter over temperature	Cause: Heat sink is overheated. Remedy: Check that the cooling air flow is not blocked. Check the ambient temperature. Clean the heatsink dust. Make sure that the switching frequency is not too high in relation to ambient temperature and motor load.
15 Motor stalled	Cause: Motor stall protection has tripped. Remedy: Check that the motor is able to rotate freely.
16 Motor over temperature	Cause: Motor overheating has been detected by frequency converter motor temperature model. Motor is overloaded. Remedy: Decrease the motor load. If no motor overload exists, check the temperature model parameters.
17 Motor underload	Cause: Motor underload protection has tripped. Remedy: Check motor and load, e.g. for broken belts or dry pumps.
22 EEPROM checksum fault	Cause: Parameter save fault: faulty operation component failure Remedy: Contact the distributor near to you. NOTE! If fault F8 occurs, find out the subcode of the fault from the Fault History menu under Id xxx!
25 Microcontroller watchdog fault	Cause: faulty operation component failure Remedy: Reset the fault and restart. If the fault re-occurs, contact the distributor near to you.
27 Back EMF protection	Cause: Drive has detected that the magnetized motor is running in start situation. A rotating PM-motor Remedy: Make sure that there is no rotating PM-motor when the start command is given.
29 Thermistor fault	Cause: The thermistor input of option board has detected increase of the motor temperature. Remedy: Check motor cooling and loading. Check thermistor connection (If thermistor input of the option board is not in use it has to be short circuited).
34 Internal bus communication	Cause: Ambient interference or defective hardware. Remedy: If the fault re-occurs, contact the distributor near to you.
35 Application fault	Cause: Application is not working properly. Remedy: Contact the distributor near to you. NOTE! If fault F8 occurs, find out the subcode of the fault from the Fault History menu under Id xxx!
41 IGBT Overtemperature	Cause: Overtemperature alarm is issued when the IGBT switch temperature exceeds 110 °C. Remedy: Check loading. Check motor size. Make identification run.
50 Analog input select 20% - 100% (selected signal range 4 to 20 mA or 2 to 10 V)	Cause: Current at the analogue input is < 4mA; Voltage at the analogue input is < 2 V. control cable is broken or loose. signal source has failed. Remedy: Check the current loop circuitry.
51 External fault	Cause: Digital input fault. Digital input has been programmed as external fault input and this input is active. Remedy: Remove the external device fault.
52 Door Panel fault	Cause: Control place is keypad, but door panel has been disconnected. Remedy: Check the connection between optional board and API. If connection is correct, contact the nearest Vacon distributor.
53 Fieldbus fault	Cause: The data connection between the fieldbus Master and the fieldbus of the drive has broken. Remedy: Check installation. If installation is correct, contact the nearest Vacon distributor.
54 Slot fault	Cause: The connection between optional board and API has been broken. Remedy: Check board and slot. Contact the nearest Vacon distributor.
55 Wrong run fault (FWD/REV conflict)	Cause: Run forward and backward are high at the same time. Remedy: Check I/O control signal 1 and I/O control signal 2.
57 Identification fault	Cause: Identification run has failed. Remedy: Run command was removed before completion of identification run. Motor is not connected to frequency converter. There is load on motor shaft.
63 Quick Stop	Cause: Quick Stop activated. Remedy: The drive has been stopped with Quick Stop digital input or Quick Stop command by fieldbus.
111 Temperature fault	Cause: Over low or over high temperature. Remedy: Check temperature signal from OPTBH board.

 

How to Read VACON 20 Faults via Panel & VACON Live

The VACON 20 interface is simple, but its internal logic can be complex due to the custom PLC features. In 2026, troubleshooting usually involves these methods:

• Built-in Display: The standard 7-segment display provides immediate status.
  • Fault (F): The drive stops modulation. The display flashes “F” followed by the code number (e.g., F1 for Overcurrent).
  • Alarm (A): The drive continues to run. The display flashes “A” followed by the code (e.g., A17 for Underload).
• VACON Live (PC Software): To diagnose deep issues, connect a PC using the VACON MCA Adapter or a standard RS-485 cable. VACON Live allows you to:
  • View the Fault History (Menu M5 on the panel, or the “Fault History” tab in software) which stores the last 9 faults with time stamps.
  • Monitor PLC internal flags if the drive is running a custom application.
• Parameter Copy: The MCA adapter can also be used to copy parameters from a faulty drive to a new one without mains power, which is critical for quick swaps in the field.

---

Frequently Asked Questions (FAQ)

Q: What is the difference between a Fault (Trip) and an Alarm?

A:

• Alarm (A-Codes): The drive detects a deviation (e.g., Motor Stalled) but continues operation. The “Ready” LED may blink.
• Fault (F-Codes): The drive stops the motor immediately to protect hardware. The red “Fault” LED lights up continuously.

Q: How do I reset a VACON 20 fault?

A:

1. Press the RESET/STOP button on the keypad.
2. Toggle the Digital Input configured for Fault Reset (Default is usually DI3).
3. Cycle the mains power (wait for the display to turn off completely).

Q: What does “F22” (EEPROM Checksum Fault) mean?

A: This usually indicates a parameter corruption or hardware failure.

• Try restoring the factory default settings (Parameter P1.13 = 1).
• If the fault persists after a factory reset, the control board memory is damaged and the drive must be replaced.

Q: Why does the drive show “F1” (Overcurrent) on startup?

A:

• Check the motor insulation (Megger test).
• Ensure the acceleration time is not too short for the load.
• If you are using the “Torque Boost” feature, reduce the setting, as it may be saturating the motor at low speeds.