Diagnose and resolve EXX error codes on the WEG CFW09 variable frequency drive. Learn how to perform a safe fault reset and implement basic preventive maintenance.

The WEG CFW09 is a heavy-duty, high-performance variable frequency drive (VFD) featuring Vectrue technology . It offers various motor control modes—including V/f (scalar), sensorless vector, and closed-loop vector with encoder feedback . To protect the motor, cabling, and the internal power components, the drive utilizes an active protection system that monitors operational variables in real-time.

WEG CFW09 Fault Codes Reference Table

Refer to your specific fault code table to cross-reference the active E00, E01, or other EXX codes currently showing on your drive's display . This helps you narrow down whether the issue lies in the incoming power lines, the motor windings, or the drive itself.

WEG CFW09 Drive Fault Codes List

Fault / Alarm and Meaning	Cause and Remedy
E00 Output Overcurrent / Short-circuit	Cause: Short-circuit between two motor phases. Short-circuit between braking resistor cables. Output current reaches 2 × P295, caused by very high load inertia, acceleration ramp too fast, or incorrect regulation and/or configuration parameters. Transistor module short-circuited. Parameters P169 to P172 are configured too high. Remedy: Check output motor cabling for phase-to-phase short-circuits. Check dynamic braking resistor connection leads for insulation wear or shorts. Reduce load inertia, or increase the acceleration ramp time. Verify control parameters and decrease parameters P169 to P172 if set too high. Reset options: Power-on, Manual reset (Key 0), Overcurrent Auto-reset, DIx, Serial, Fieldbus.
E01 Overvoltage (Ud) / DC Link Overvoltage	Cause: The DC-bus voltage of the inverter has exceeded the permissible limits (check Ud in parameter P004): 220-230 V Models: Ud > 400 V 380-480 V Models: Ud > 800 V 500-600 V / 500-690 V Models (supply 500-600V): Ud > 1000 V 500-690 V / 660-690 V Models (supply 660-690V): Ud > 1200 V Load inertia too high or deceleration ramp too short. Parameters P151 or P153 are configured too high. Remedy: Verify incoming mains supply voltage stability (P004). Increase deceleration ramp time or reduce load inertia. Use a dynamic braking resistor if necessary. Decrease parameters P151 or P153 if set too high. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E02 Undervoltage (Ud) / DC Link Undervoltage	Cause: The DC-bus voltage of the inverter has fallen below the permissible limits (check Ud in parameter P004): 220-230 V power supply: Ud < 223 V 380 V power supply: Ud < 385 V 400-415 V power supply: Ud < 405 V 440-460 V power supply: Ud < 446 V 480 V power supply: Ud < 487 V 500-525 V power supply: Ud < 532 V 550-575 V power supply: Ud < 582 V 600 V power supply: Ud < 608 V 660-690 V power supply: Ud < 699 V Phase loss at the input. Auxiliary circuit fuse blown (only valid for 105 A and 130 A/220-230 V, 86 A to 600 A/380-480 V, and 44 A to 79 A/500-600 V models). Pre-charge contactor is defective. Parameter P296 is set to a voltage higher than the actual power supply voltage. Remedy: Check input mains voltages. Check terminal blocks and check for missing phases. Verify pre-charge contactor and auxiliary circuit fuses (refer to manual section 3.2.3). Ensure parameter P296 matches your actual rated supply voltage. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E03 Input Undervoltage / Phase Loss	Cause: Power supply voltage is too low, check supply line voltage: 220-230 V Models: Power Supply < 154 V 380-480 V Models: Power Supply < 266 V 500-600 V / 500-690 V Models: Power Supply < 361 V 660-690 V Models: Power Supply < 462 V Phase loss at the inverter input. Activation Time limit: 2.0 s. Remedy: Check mains supply line for phase drops or drops in voltage. Verify general supply voltage stability. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E04 Inverter Overtemperature or Pre-charge Circuit Defective	Cause: Ambient temperature too high (> 40 °C) and/or output current too high; or ambient temperature < -10 °C. Cooling blowers are locked or defective. Auxiliary circuit fuse blown (only valid for 105 A and 130 A/220-230 V, 86 A to 600 A/380-480 V, and 44 A to 79 A/500-600 V models). Problem with the supply voltage (voltage sag or interruption/phase loss lasting for more than 2 seconds) with the phase loss detection disabled (P214 = 0). Inverted polarity signal at Analog inputs AI1/AI2. Remedy: Verify cooling fan is functioning and clean any dust from the heatsink. Improve cabinet airflow. Verify ambient working temperatures (ensure between -10 °C and 40 °C). Check supply lines and auxiliary circuit fuses (refer to manual section 3.2.3). Verify polarity on analog input channels AI1/AI2. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E05 Inverter / Motor Overload (I × t Function)	Cause: Parameters P156, P157, and P158 are configured too low for the connected motor. Motor is under an actual overload condition. Remedy: Verify motor nominal currents and check P156, P157, and P158 against nameplate data. Check mechanical load on shaft. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E06 External Fault	Cause: Any digital input (DI3 to DI7) programmed for external fault detection (parameters P265 to P270 set to 4 – No Ext Flt) is open (not connected to +24 V). Terminal block XC12 on the control board CC9 is not properly connected. Remedy: Verify external cabling loops to the assigned digital inputs. Ensure terminal block XC12 on the control board CC9 is fully seated. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E07 Encoder Fault	Cause: Miswiring between encoder and terminal block XC9 (optional board EBA/EBB/EBC/EBE). Encoder is defective. Note: This fault is valid only if P202 = 4 (Vector with Encoder). Remedy: Check encoder connection sequence to XC9. Verify mechanical mounting of encoder (refer to manual section 8.2). Swap encoder if defective. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E08 CPU Error (watchdog)	Cause: High electrical noise. Remedy: Optimize cabinet grounding and shield terminations to mitigate noise. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E09 Program Memory Error (Checksum)	Cause: Memory with corrupted values. Remedy: This indicates internal card memory failure. Please contact WEG technical support. Reset: Contact WEG.
E10 Error in the Copy Function	Cause: Attempted to copy HMI parameters to an inverter with a different software version. Remedy: Verify firmware and software versions match between target inverter and HMI file before copying. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E11 Ground Fault	Cause: Short-circuit between one or more output phases and ground. Motor cable capacitance to ground is too high. Remedy: Verify insulation of motor cables and motor winding. If cable is extremely long, shorten lines or add an output reactor. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E12 Braking Resistor Overload	Cause: Load inertia too high or deceleration ramp too short. Load on the motor shaft too high. Parameters P154 and P155 are programmed incorrectly. Remedy: Increase deceleration ramp time. Adjust mechanical shaft load. Verify and correct parameter configurations for P154 and P155. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx.
E13 Incorrect encoder sense of rotation	Cause: Cables U, V, W to motor are inverted. Encoder channels A and B are inverted. Encoder mounted in wrong position. Note: This is valid for P202 = 4 (Encoder), with P408 = runs to Imr. This fault can only occur during Self-tuning. Remedy: Do not reset this fault and restart without first correcting the direction of either the encoder or the motor. Swap motor output phases (U, V, W) or invert encoder channels A and B. Correct physical mount orientation of the encoder.
E15 Motor Phase Loss	Cause: Bad contact or broken wiring between motor and inverter. Incorrect value programmed in parameter P401. Vector Control without orientation. Vector Control with encoder, encoder wiring or connection to motor is inverted. Remedy: Check motor cables and winding loop continuity. Verify parameter P401 rating settings. Review vector control orientation parameters and check encoder connections. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E17 Overspeed Fault	Cause: The effective overspeed has exceeded the value of P134 + P132 for longer than 20 ms. Remedy: Verify speed loop tuning and speed feedback channels. Check mechanical load variations.
E24 Programming Error	Cause: Incompatible parameters were programmed (refer to manual Table 4.2). Remedy: This fault is automatically reset when the incompatible parameters are correctly programmed. Resolve conflicting parameter values according to manual Table 4.2 definitions.
E31 Keypad (HMI) Connection Fault	Cause: Keypad cable misconnected. Electrical noise in the installation (electromagnetic interference). Remedy: This fault is automatically reset when HMI communication with the inverter is reestablished. Check keypad RJ45/serial cable connections. Protect the cable from electromagnetic noise.
E32 Motor Overtemperature	Cause: Motor is under an actual overload condition. Duty cycle is too high (too many starts/stops per minute). Ambient temperature is too high. Motor thermistor miswiring or short-circuit (resistance < 100 Ω) at terminals XC4:2 and XC4:3 of the optional board EBA or at terminals XC5:2 and XC5:3 of the optional board EBB. Parameter P270 programmed to 16 unintentionally, with EBA/EBB board not installed and/or motor thermistor not connected. Motor is in locked rotor condition. Note: Overtemperature protection (4). Remedy: Check motor load status and duty cycles. Reduce starts/stops per minute. Verify thermistor cabling loop resistance is not < 100 Ω. Check configuration parameter P270. Verify motor shaft is free to rotate. Reset options: Power-on, Manual reset (Key 0), Auto-reset, DIx, Serial, Fieldbus.
E33 Speed without Control	Cause: Overweight load conditions. Brake Failure. Note: Control parameter (8). Remedy: Check mechanical brakes and load stability.
E34 Long Period at Torque Limitation	Cause: The load was too heavy and the CFW-09 operated at torque limitation for a period longer than allowed. Failure on the brake opening caused the CFW-09 to operate at torque limitation for a period longer than allowed. Note: Torque limit parameter (9). Remedy: Reduce motor load. Verify brake opening coil, connections, and limit switches.
E41 Self Diagnosis Fault	Cause: Memory error or any internal inverter circuit defective. Remedy: Contact WEG technical support for control card evaluation. Reset: Contact WEG.

Methods to Reset a WEG CFW09 Fault

Once you have diagnosed the fault and addressed the root cause, you must clear the trip status to allow normal motor operation to resume. The CFW09 supports several methods to perform a reset :

1. Power Cycle (Power-On Reset): Disconnect the main AC power supply . Safety Requirement: Wait at least 10 minutes to allow the internal DC-link capacitors to discharge to safe voltage levels before touching any electrical terminals or re-applying power.
2. HMI Manual Reset: Press the red O/RESET key on the front control panel .
3. Digital Input Reset: If one of the digital inputs (DI1 to DI6) is configured for "Reset" via parameters (P265 to P270 configured to value 12), you can pulse this input to clear the fault remotely .
4. Auto-Reset Parameter: You can configure parameter P206 to automatically clear minor transient faults after a programmed delay . It is recommended to use this feature with caution to prevent the drive from repeatedly starting into hard electrical faults.
5. Serial/Fieldbus Reset: If the VFD is connected to an external network (such as DeviceNet or Modbus), you can transmit a fault reset command bit via the fieldbus control word .

Most Common CFW09 Faults and Quick Diagnostics

While the fault list covers many scenarios, a few primary errors account for most field trips on industrial installations:

1. E00 (Output Overcurrent / Short-Circuit)

E00 indicates that the drive has detected a sudden current spike at its output terminals . This can be caused by a short-circuit between the motor phases, a ground fault in the motor cabling, high motor cable capacitance, or an IGBT transistor failure .

• Diagnostic: Disconnect the motor leads from the drive and perform an insulation test (megger test) on the motor cables and winding. If the E00 fault persists even when the motor is disconnected, the drive’s internal power module may require service .

2. E01 (DC Link Overvoltage)

E01 is triggered when the voltage on the drive’s internal DC bus exceeds its maximum safety threshold . This is most common during rapid motor deceleration when the load regenerates kinetic energy back into the drive .

• Diagnostic: Try increasing the deceleration ramp time (P101 or P103) to decelerate the load more slowly. If your application has a high-inertia load that must stop quickly, verify that your dynamic braking resistor is correctly sized and wired to the braking terminals .

3. E02 (DC Link Undervoltage)

An undervoltage trip occurs when the DC bus voltage drops below the minimum operating level . This is often caused by incoming utility voltage sags, a blown input fuse, or a failing input contactor .

• Diagnostic: Measure the incoming line voltage under load to ensure it remains stable and within the specified limits of the drive's nameplate.

4. E04 (Overtemperature at Power Assembly)

This code indicates that the drive's heatsink temperature has exceeded safe limits . It is typically caused by restricted cooling airflow or high ambient temperatures inside the cabinet .

• Diagnostic: Check that the cooling fan is running properly, clean any dust or oil accumulation from the heatsink fins, and verify that the enclosure vents are clear of obstructions . Let the drive cool down for a few minutes before attempting a reset .

Preventative Maintenance Tips for the CFW09

Keeping the CFW09 in clean, stable conditions can help prevent unexpected trips and prolong its overall service life:

• Utilize the Keypad Copy Function: The CFW09 HMI allows you to copy and store up to two complete parameter sets . Saving your custom configuration onto the keypad is a useful practice before performing maintenance, as it ensures you can easily restore your settings if a unit ever needs replacement .
• Periodically Check Terminal Torque: Thermal expansion and mechanical vibration can loosen power and control terminal screws over time. Periodically check and retorque all incoming power, motor, and ground connections to prevent phase loss or hot joints.
• Control Cabinet Ventilation: Keep the drive free of moisture, oil mist, and conductive dust, which are common causes of premature failure in industrial environments.

By responding to warning signs and maintaining stable environmental conditions, you can optimize the lifespan and reliability of your WEG CFW09 drive.