Norcold Refrigerator: “Sr FS / Sr”
warning RV refrigerator error codes
What it means
The flame-sense circuit inside the control has failed, so the refrigerator can no longer tell reliably whether the gas burner is alight. This is a fault of the sensing electronics, not of the fuel supply. The older LED panel alternates "Sr" and "FS" with the AC LED flashing; the LCD panel simply flashes "Sr".
Most likely causes
- Failed flame-sense circuit on the rear power board most likely
- Damaged or shorted spark/sense lead between the electrode and the board common
Safe checks you can do yourself
- Cycle the refrigerator OFF and ON to confirm the code returns rather than being a one-off
- With the fridge off and cool, check the spark/sense lead at the burner for chafing, soot or a loose spade connector
How to reset / clear Sr FS / Sr
- Cycle the refrigerator OFF and ON once to rule out a momentary glitch
- A repeating fault is board-level and will not clear with a normal reset
When to call a technician
The code returns after a power cycle. Norcold's instruction for this fault is to replace the power board.
Accuracy notes
Added on 2026-08-30 during a correction pass. Do not confuse it with "no FL", which means the burner did not light at all (a fuel, gas-pressure or ignition problem), or with "AC rE" / "Sr CL", which is the AC relay stuck closed. On Polar N7/N8 models the controls report their internal faults as two or three flashes instead, and a flame sensed when none should be present is five flashes.
Applies to
1200 · 1201 · 1210 · 1211 · N640/N641/N840/N841 (shown as "Sr") · N620/N621/N820/N821 (shown as the letter "S")
FAQ
What does Norcold Refrigerator code "Sr FS / Sr" mean?
The flame-sense circuit inside the control has failed, so the refrigerator can no longer tell reliably whether the gas burner is alight. This is a fault of the sensing electronics, not of the fuel supply. The older LED panel alternates "Sr" and "FS" with the AC LED flashing; the LCD panel simply flashes "Sr".
How do I reset Norcold Refrigerator Sr FS / Sr?
Cycle the refrigerator OFF and ON once to rule out a momentary glitch. A repeating fault is board-level and will not clear with a normal reset.
What is the most common cause of Sr FS / Sr on a Norcold Refrigerator?
The most likely cause is failed flame-sense circuit on the rear power board.
Related · Norcold refrigerator
The refrigerator tried to run on LP/propane (gas) mode but the control… AC rE / Sr CL
The AC relay on the rear power board is stuck closed, so the control can…
Sources
- Norcold 1200XX / 120X-IMXX Refrigerator Service Manual, "Sr FS - Sr Fault Code - Flame sense circuit failure" (p. 10) — 618968B p.10: "Sr" and "FS" flashing with AC LED flashing, or "Sr" flashing = flame sense circuit failure. Replace power board. (Thetford Corp. / Norcold, Inc. (OEM), Publication No. 618968B)
- Norcold N6XX/N8XX Models Refrigerator Service Manual, Fault Codes table — N640/N641/N840/N841: "Sr" = flame sense circuit has failed; N620/N621/N820/N821: "S" = flame sense circuit has failed (Norcold, Inc. (OEM), Publication 619394E)
● Checked against 2 manufacturer documents · Last verified 2026-08-30 · compiled from manufacturer documentation. Codes can vary by model year — always cross-check your unit’s manual. How we verify