What i55 / i56 Means
i55 and i56 are DC link voltage codes from the motor control board. i55 is overvoltage above 392 volts DC, clearing when it drops under 390. i56 is undervoltage: the board’s internal voltage fell below 225 volts DC and clears above 260.
Common Causes of i55 / i56
- Supply voltage spikes or sags
- Motor control board power stage failing
🔧 One Safe Check You Can Try
Note whether the codes appear during storms or when heavy appliances start. A reset at the breaker is the owner step.
⚠ Why You Shouldn't Go Further Than That
- DC link voltages of several hundred volts are dangerous to measure.
- The motor control board is replaced as a unit.
Opening a panel to inspect or repair something yourself doesn't automatically cancel your manufacturer's warranty — but it can risk accidental damage, and some manufacturers do have specific service conditions. Check your product's warranty terms, or ask us, before deciding.