What Happens When a Crank Position Sensor Fails?

by Heather Potter

The crankshaft position sensor is used in engine ignition systems without electronic distributors. Crankshaft position sensors come in two varieties -- Hall effect and magnetic.

How It Works

The sensor sends a signal to the powertrain control module, which tells the PCM the position of the number one cylinder and crankshaft. The PCM uses the signal from the crank position sensor to calibrate ignition timing and operate the fuel injectors. The sensor indicates how fast the engine is running, and the PCM adjusts ignition timing accordingly.


The vehicle's engine will not work without the signal from the sensor. Sometimes the engine will crank after sensor failure but the engine won't start.

Causes of Failure

Problems with the sensor wiring harness are the most common reason for sensor failure. Hall effect sensors can suffer a loss of supply voltage, which also leads to timing signal loss.

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