Underheat issue

[dron0gus]

Start feeding pump before reaching target temperature (close loop). Otherwise if mixture is lean, nernst voltage is too close to virtual ground and voltage on output of differential op amp can be clamped at 0V thus causing incorrect ESR measurement. Incorrectly measured ESR cause incorrect (higher than actual) calculated temperature and SW can fall into overheat state. Not sure if it is safe to start feeding pump at defined temperature.