How Does an Engine Pick Up Coil Work?

by Andrea Stein
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sand car engine image by Clarence Alford from

A distributor is an ignition system device used by a vehicle’s engine to send voltage to the spark plugs from the ignition coil in the proper firing order. The engine’s pick up coil determines this firing order.


A pick up coil refers to a sensor device contained in a rotor. The sensor is composed of a transducer which changes output based on how a magnetic field is altered.


The rotor is mounted to the distributor shaft, which is spun via a gear driven by the camshaft. Small openings, or windows in the rotor, match in number to the number of engine cylinders. The rotor spins, enabling these windows to pass by the pick up coil sensor. This in turn causes the pick up coil sensor to pass by a permanent magnet located outside of the rotor, which activates a signal. The signal is transmitted to the ignition system, which is then able to determine the correct firing order.


A defective pick up coil can cause the spark plugs to not receive the proper instructions to fire, resulting in no engine spark. Defective or malfunctioning pick up coils can also cause the fuel injectors to not activate, also resulting in an inability to start the vehicle. In such situations, the pick up coils should be checked and possibly replaced.

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