How to Test Cam Sensors With an Ohm Meter

by Michael O. Smathers

If your car begins sputtering or refusing to start, the problem could lie with a faulty camshaft sensor. Camshafts are connected to your engine's crankshaft and cause the valves to compress. According to Merced College, the camshaft sensor relays information to the fuel injector computer and times the spark that ignites the fuel-air mixture. A faulty cam sensor could disrupt the timing of your engine's stroke cycle. Testing its electrical resistance with an ohmmeter or multimeter allows you to troubleshoot the cam sensor. Cam sensor resistances and the location of the sensor vary with your vehicle's make and model.

Step 1

Move your vehicle to a well-lit area. Turn it off and wait several hours for the engine to cool off. For safety purposes, disconnect your car's positive and negative battery terminals by unscrewing the nuts near them with the 1/2 inch wrench and removing the terminals from the posts. Avoid allowing them to contact anything metal.

Step 2

Consult your owner's manual to determine the location of your camshafts and sensors. Access them; you may need to remove other engine components in the process.

Step 3

Connect the red lead of your meter to the socket marked "VO+." Connect the black lead to the socket marked "COM." Set your meter to the ohms setting if necessary. According to Harvard University, the symbol for ohms is the Greek letter "omega," which resembles a horseshoe.