If the wires on an O2 sensor have been broken off will engine act like it is starved for fuel?

Yes, if the wires on an O2 sensor are broken, the engine computer (ECU) will likely default to a "fail-safe" mode. This often involves running a richer air/fuel mixture than optimal. While not precisely "starved for fuel," the engine will run inefficiently, and you might experience symptoms similar to a lean condition, such as:

* Reduced power: The engine won't produce its normal horsepower.

* Poor fuel economy: You'll get fewer miles per gallon.

* Rough idling: The engine may run unevenly at idle.

* Hesitation or stumbling: The engine may hesitate or stumble when accelerating.

The reason is that the ECU relies on the O2 sensor's readings to adjust the air/fuel mixture. Without a signal, it can't accurately determine the correct mixture and resorts to a pre-programmed, richer setting to avoid potentially damaging a lean condition (which is far more detrimental to the engine). This richer mixture is wasteful and less efficient.