Exceptional points (EPs) have been suggested for ultrasensitive sensing because the eigenfrequency splitting grows as the $n\mathrm{th}$ root of a perturbation, suggesting divergent responsivity. In ideal linear devices, this responsivity gain is canceled by a matching divergence in the quantum shot-noise floor. Similar arguments have been applied to nonlinear devices, such as above-threshold lasers. However, this cancellation framing relies on an unphysical divergence in frequency noise and linewidth. We show that for a system of coupled saturable resonators, a self-consistent treatment of higher-order fluctuation dynamics removes these divergences entirely: the EP of the time-averaged Hamiltonian can be reached, but no longer yields unbounded responsivity. The EP of the fluctuation operator is, in principle, singular, but stochastic forcing shifts the steady state away, so the system cannot operate at this EP. This noise-induced shift results in finite plateaus for both responsivity and linewidth. Stochastic Langevin simulations of the full nonlinear system corroborate our results down to zero detuning.

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• Photonics
• Rotation sensing
• Exceptional points
• PT-symmetry