Modern control systems often protect against a single misleading sensor by comparing it with another source. Electronic throttle systems compare two pedal tracks and usually two throttle-position tracks. Stability control compares steering angle, yaw rate, lateral acceleration and wheel speeds. Climate systems compare commanded operation with refrigerant pressure and evaporator temperature.
This means a sensor can be electrically within range and still be wrong. If a coolant sensor reads 40°C when the engine is actually 90°C, the value is not open-circuit or short-circuit, yet it may cause poor fueling or fan behavior. The ECU may or may not set a code, depending on how implausible the value becomes relative to other information.
Correlation is one of the most powerful diagnostic ideas in this book. Ask which other measurement should agree with the suspect sensor. Key-off MAP can be compared with barometric pressure. Four wheel speeds can be compared with one another. Engine speed from the crank sensor can be compared with cam synchronization. Battery voltage on a scan tool can be checked with a meter at the module supply.
A diagnostic conclusion is stronger when several independent pieces of evidence point to the same fault.