LG · Oven Serious

F5 — Lower oven thermistor error

The lower oven temperature sensor is reading open or short, or its value is outside the legal range. On double ovens this isolates to the lower cavity only.

Keep using it?
Limited use only
DIY difficulty
Moderate
Verified against
lg.com ↗

How to fix it

  1. Press CLEAR/OFF; if F5 returns, kill the breaker for 30 seconds and retry.
  2. Disconnect power, pull the lower-oven rear panel, and unplug the lower thermistor.
  3. Measure resistance at room temperature — should be ~1080 Ω. Replace if open, shorted, or far off.
  4. Inspect the harness between the sensor and the control board for chafe or burn marks.
  5. Reseat the connector at both ends and retest.
  6. If sensor and wiring are good, replace the lower-oven control board.

Why it happens

Typical signs: F5 or F-5 on display · Lower oven will not preheat or holds wrong temperature · Upper oven still works on double-oven models

  • Failed lower-oven thermistor Sensor element drifted, open, or shorted.
  • Broken sensor harness inside the rear cavity Connector backed off the sensor pigtail.
  • Corroded sensor connector Steam cleaning or self-clean exposure corroded the pins.
  • Lower-oven control board fault Sensor input circuit on the PCB has failed.

Parts you may need

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • LG lower oven thermistor Common replacement
    Amazon →

More LG oven codes

5b 5b — Sabbath Mode active (not a fault) CF1 CF1 — Left-front cooktop sensor open/short CF2 CF2 — Left-rear cooktop sensor open/short CF3 CF3 — Right-front cooktop sensor open/short CF4 CF4 — Right-rear cooktop sensor open/short F1 Range F1 — Upper Oven Thermistor Error

All LG codes → All oven codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: lg.com.