What causes fault code VFD-AIF1 (VFD Analog Input Signal Loss)?

Analog signal wire broken or disconnected. Transmitter/controller sending the signal has faulted. Shield not grounded properly — electrical noise corrupting signal. Analog input terminal corrosion — high-resistance connection. Wrong signal type selected — drive expects 4-20mA but receiving 0-10V

How do I fix fault code VFD-AIF1?

Measure analog signal at drive input terminals with multimeter. For 4-20mA: should read 4mA minimum. Below 3.5mA = signal loss. For 0-10V: should read >0.5V normally. 0V = signal loss. Check wiring from source to drive — repair any breaks. Verify signal source is outputting correct range. Clean terminal connections — remove corrosion. Set drive fault-on-signal-loss action: coast, run at preset speed, or fault

VFD Analog Input Signal Loss

VFD-AIF1

4-20mA or 0-10V analog speed reference signal dropped below minimum threshold or was lost entirely.

medium vfd

vfd analog 4-20mA signal loss reference

Probable Causes (ranked)

Analog signal wire broken or disconnected
Transmitter/controller sending the signal has faulted
Shield not grounded properly — electrical noise corrupting signal
Analog input terminal corrosion — high-resistance connection
Wrong signal type selected — drive expects 4-20mA but receiving 0-10V

Fix Steps

1 Measure analog signal at drive input terminals with multimeter
2 For 4-20mA: should read 4mA minimum. Below 3.5mA = signal loss
3 For 0-10V: should read >0.5V normally. 0V = signal loss
4 Check wiring from source to drive — repair any breaks
5 Verify signal source is outputting correct range
6 Clean terminal connections — remove corrosion
7 Set drive fault-on-signal-loss action: coast, run at preset speed, or fault

Field Trick

Disconnect the signal wire at the drive and jumper a 9V battery across the analog input (with a 500 ohm resistor for 4-20mA). If the drive responds, your signal source is the problem.

Need a deeper diagnosis with photo analysis and AI-powered troubleshooting?

Run Full Diagnosis