How to Test the Sentra Crank Position Sensor

The crank position sensor in a Nissan Sentra is designed to provide the engine control module (ECM) with information about the position of the crankshaft in relation to the camshaft and engine block. A faulty crank position sensor will prevent the engine from starting, because the ECM cannot determine when to fire the ignition. Replacement crank position sensors are available from Nissan dealerships, local auto parts stores and online auto parts websites.

Things You'll Need

  • Automotive scan tool


    • 1

      Shift the Sentra's transmission into park or first gear (manual transmission) and turn off the engine. Set the parking brake and turn the ignition back to the "ON" position. Don't start the engine.

    • 2

      Connect an automotive scan tool to the Sentra's diagnostic data port, located underneath the dash on the driver's side.

    • 3

      Turn on the scan tool and select "ECM" from the main menu screen. Select "Live Data" from the secondary menu screen. Select "CKP Sensor" from the "Live Data" screen.

    • 4

      Rotate the ignition switch forward and attempt to start the engine. Look at the scan tool's screen while the engine is cranking; it should display the cranking RPM of the engine. If it does not, then the crank position sensor is faulty and must be replaced.

Tips & Warnings

  • Automotive scan tools are portable diagnostic computers that are used to perform tests and other procedures on vehicles. They are available from local auto parts stores and other tool retailers.
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