Sub-Zero Classic BI Code 40-2-38: Freezer FET output error

What 40-2-38 means

Classic built-ins such as the BI-36UFD/S use 40-2-38 for a freezer FET power output error, meaning a board output on the freezer side is not working as intended. The available description repeats the refrigerator stepper valve wording, which appears to be a copy slip, so we treat this as the freezer output on the control board. The freezer may run warm, cycle unpredictably or stop cooling while the fresh food section continues normally.

Common causes of 40-2-38

Freezer FET output on the control board not switching
Wiring from that output loose or damaged
Load on that output drawing incorrectly

✓ One safe check you can try

1. Check the freezer temperature and move frozen goods if it rises. 2. Reset power at the breaker for one minute. 3. Note whether the code returns quickly or after some time. 4. Keep the door closed and avoid loading warm items.

! Why to stop there

Board outputs must be tested with power on.
Wiring at the board must be checked against the diagram.
Replacement boards need the correct model setup.

Opening a panel yourself does not automatically cancel a manufacturer warranty, but it can cause accidental damage, and some manufacturers set their own service conditions. Check your warranty terms, or ask us, before deciding.

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Other Refrigerator codes

80Sub-Zero 700TF Code 80: No inverter feedback after a board change ddSub-Zero 600 and 700 Series Display dd: Diagnostics switched off deSub-Zero 600 and 700 Series Display de: Diagnostics enabled 23Sub-Zero 600, 700 and 648PRO Code 23: Defrost overheat with no feedback 50Sub-Zero 600 and 700 Series Code 50: Refrigerator compressor running too long 41Sub-Zero 648PRO Code 41: Zone compressor or wiring problem 81Sub-Zero 700-2 Code 81: Variable-Speed compressor fails to start 82Sub-Zero 700-2 Code 82: VS compressor controller needs replacement

40-2-3840-2-38 questions

Why does the description mention the refrigerator?

The text published for 40-2-38 repeats the refrigerator stepper valve wording, which looks like a copy slip. The title clearly refers to the freezer, so we test the freezer-side output and its wiring.

Is the freezer going to stop?

It may cool poorly or cycle unpredictably while the output misbehaves. Watch the freezer temperature with a thermometer, and move valuable food to another freezer or a cooler with ice if it starts to warm.

What does fixing this code take?

We test the freezer-side output on the control board and the wiring it feeds, then quote the repair in writing before anything is replaced. Our 30-day workmanship warranty covers the work.