Sub-Zero Refrigerator Error Code 90 5 73

Error code 90 5 73 indicates an invalid log fault checksum, meaning the control board has detected a mismatch between stored data and the expected checksum value in its internal fault log memory. This is a firmware and data integrity issue rather than a problem with a specific component like a sensor or compressor. The refrigerator may continue to operate normally, but the error signals that the board's memory may be corrupted or unreliable.

A power reset may clear the error if it was triggered by a one-time event such as a brief power outage or surge. However, if the control board's memory has sustained actual corruption, the error will return after the reset. A reset is always a reasonable first step, but a recurring code points to a hardware issue with the control board.

If a power reset resolves the error, there is no parts cost involved. If the main control board requires replacement, parts and labor costs for a Sub-Zero refrigerator typically range from several hundred dollars to over one thousand dollars depending on the specific model and local labor rates. Getting a diagnostic evaluation from a Sub-Zero authorized service technician before committing to a repair is advisable.

The first step is to perform a full power reset by unplugging the refrigerator or turning off the circuit breaker for several minutes, then restoring power. If the error clears and does not return, a transient power interruption was likely the cause. If the code returns after a reset, the main control board likely has a persistent memory fault and a qualified technician should evaluate the unit.

In many cases the refrigerator will continue cooling normally even when this error is present, since the fault relates to memory data logging rather than a core operational function. However, a corrupted control board may also affect other functions over time, so the issue should not be ignored indefinitely. Monitor food temperatures to confirm the unit is maintaining safe cooling while you arrange for service.