How To Test A Crankshaft Position Sensor With A Scanner Or Multimeter

There are a number of common symptoms of a bad crankshaft position sensor (CKP) that can help you determine if your sensor has failed, including engine misfires, rough idling, stalling, or hard starting. If you are experiencing problems like these, you might need to replace your crankshaft position sensor.

However, these same symptoms can be caused by problems with your ignition or fuel injection systems, too. So before you replace your crankshaft position sensor, you might want to run some tests to determine that the crank sensor really is the source of the problem. Here is how to test a crankshaft position sensor with or without a code:

CKP Trouble Codes

If your check engine light is on, then your engine control unit (ECU) has recorded some sort of trouble code. You can check onboard diagnostic trouble codes with a diagnostic scan tool. Codes between P0335 and P0338 correspond to crankshaft sensor problems.

This is probably the most straightforward and the most certain way to test for and identify a crankshaft sensor problem. Unfortunately, the crankshaft sensor is usually pretty worn by the time that the check engine light is on. You might already be experiencing crankshaft sensor problems before the ECU has noted any sign of trouble. If you want to be proactive, there is some other testing you can do.

Cranking the Engine and Reading RPM

This next crank sensor testing technique also uses a diagnostic scan tool. One of the settings of the scanner allows you to read the engine speed in revolutions per minute (RPM). Now, can you guess where the scanner gets that information from? If you guessed the crankshaft position sensor, then you would be correct. Set up the scanner to read engine RPM and crank the engine. The scan tool should read between 100 and 500 RPM. A bad reading indicates that the crankshaft sensor isn't working right. A reading of zero indicates that the crankshaft sensor has failed completely.