Frigidaire Cooktop Error Code E91

The E91 error code on a Frigidaire induction cooktop indicates an internal generator synchronization fault within the 2-cook-zone induction module. Induction cooktops rely on high-frequency generator circuits to produce the oscillating magnetic fields that heat cookware. When two cook zones share or communicate through a common induction module, their generator circuits must remain synchronized. If the control system detects that the sync signal between the two generator circuits has failed or fallen outside acceptable parameters, it triggers the E91 fault and halts operation to prevent component damage.

The right generator circuit board is the primary focus of diagnosis for this fault. This board contains the power electronics and timing components responsible for driving the induction coils in the affected zones. A loss of synchronization can result from a failed connection along the signal or power cables linking the generator board to the main control board, a damaged generator board itself, or a fault within the induction module housing both cook zones. Loose, corroded, or broken cable connectors are among the most frequent root causes and should be inspected before condemning the board.

Because this fault involves high-voltage power electronics, all diagnostic work should be performed with the cooktop fully disconnected from the power supply before handling internal components. Technicians should visually inspect all ribbon cables and wire harnesses connected to the right generator circuit board, check for signs of heat damage or arcing, and reseat all connectors firmly before re-energizing the unit to test for fault recurrence.