A faulty camshaft sensor results in numerous problems with a car, including an illuminated check engine light, a poorly running engine and difficulty or failure to start. The camshaft sensor replaces the distributor in many modern cars, and if it malfunctions, the spark plugs fail to fire correctly. According to O'Reilly Auto Parts, faulty camshaft sensors are the 11th most common automotive repair.
The camshaft sensor monitors the position of the camshaft and sends the information to the car's electronic control module. This on-board computer uses the information along with information sent by other sensors throughout the drivetrain to determine when each spark plug should fire. When the sensor is bad, the control module has no way of knowing the location of the camshaft.
Camshaft sensors normally do not fail immediately. Damage from wear and tear or accidents causes them to become less effective at transmitting their signal. When the sensor first starts to malfunction, the car remains drivable, but the operator may notice an occasional engine miss or the vehicle becoming more difficult to start. A sensor that is already malfunctioning grows worse with extremes in temperature that come with seasonal changes. Drivers who suspect a problem with the sensor should have a mechanic check and replace it to ensure that the vehicle starts when temperatures start to change.