Dacor oven F3 vs F4 both concern the oven temperature sensor on Legacy Classic ERC wall ovens — the ECS/ECD, PCS/PCD, and MCS/MCD families — documented in Dacor’s own Tec-Line troubleshooting sheet as a matched pair of Medium-severity problems describing opposite electrical conditions in the same circuit.
F3: shorted oven temperature sensor
F3 means the sensor circuit is shorted — reading as a closed connection where the control expects variable resistance that changes with temperature. A shorted sensor typically reads as an extreme, unchanging temperature value to the control board, which is why the ERC flags it rather than simply displaying an inaccurate but plausible temperature.
F4: open oven temperature sensor circuit
F4 means the opposite electrical condition — the sensor circuit is open, with no continuous path for the control board to read a resistance value from at all. This can result from a broken sensor wire, a failed connector, or the sensor probe itself failing internally in a way that breaks the circuit rather than shorting it.
Why the distinction matters for diagnosis
A shorted sensor (F3) and an open sensor circuit (F4) point toward different physical failure modes even though both concern the identical sensor and wiring run. A visibly damaged or pinched sensor wire is more consistent with an open circuit; a sensor that has failed internally in a way that creates a short is a different physical failure inside the same small component. Knowing which code displayed narrows what a technician checks first, even though the eventual fix — replacing the sensor or the affected wiring — often looks similar either way.
What these two do not indicate
Neither F3 nor F4 means the ERC board itself has failed — both are specifically sensor-and-wiring failures, distinct from board-level codes like F5 or F6, which call for ERC replacement instead. Confirming F3 or F4 specifically, rather than assuming a board problem, keeps the repair scoped to the smaller, less expensive component.
What to check before calling
Visible damage to the sensor probe itself, typically mounted inside the oven cavity, or to its wiring where it runs toward the back of the appliance, is worth a look if it is safely accessible, though confirming the actual electrical problem (short versus open) requires meter testing a technician would perform.
When to book service
Either F3 or F4 recurring after a power cycle points toward sensor or wiring replacement rather than a board-level repair, and is worth an experienced technician’s diagnosis to confirm which. Our oven error codes page covers both codes in the full Classic ERC table, and our oven appliance page covers current and Legacy models. Schedule a visit with the exact code noted, and see Dacor’s own site for current oven models.
