A faulty magnetic pick up (crankshaft position sensor) will cause?

A faulty magnetic pick-up, or crankshaft position sensor, directly affects the engine's ability to determine the precise position of the crankshaft, which is critical for ignition timing and fuel injection control. When this sensor malfunctions, it may not send the necessary signals to the engine control module (ECM), leading to a no-start condition. The ECM relies on this information to fire the spark plugs at the correct time and to accurately inject fuel into the engine. Without the proper signals from a functioning crankshaft position sensor, the engine may not start at all.

While a faulty sensor can contribute to issues like rough idle under certain circumstances, the most immediate and clear symptom of failure is typically a no-start scenario, as the engine management system cannot operate correctly without the necessary positional data.