# 20 — Appliance fault and error codes

For 20, brand is Sub-Zero; appliance type is refrigerator; meaning is Freezer-defrost underheat condition with missing feedback at defrost start, verified against its source on 2026-08-04.

- **Brand:** Sub-Zero
- **Appliance type:** refrigerator
- **Error code:** 20
- **Meaning:** Freezer-defrost underheat condition with missing feedback at defrost start.

## What the source says

> freezer-defrost underheat condition with missing feedback at defrost start.

## Source

- https://faultcodelab.com/data/error-codes.v1.json

Last verified: 2026-08-04. Review by: 2027-08-04.
Part of [Appliance fault and error codes](https://referencesource.org/appliance-fault-error-codes/).