The camshaft position sensor tells the computer what position the camshaft is in, and the computer calculates ignition and fuel injection timing from this signal. The symptoms of a faulty camshaft position sensor can be a hard start or a no start, depending on the manufacturer.
The camshaft will be located in one of three places, depending on the manufacturer: on the side of the engine block, on the back of the cylinder head or in the lifter valley. To find the location of your vehicle's camshaft position sensor, visit autozone.com and locate a free repair guide for your vehicle (see Resources).
Remove the wiring and retaining screws of the sensor, then slide it out of its mounting hole. Examine the sensor for damage from impact, as this may indicate movement in the camshaft or sludge buildup that will need to be addressed before replacement. To replace, simply insert the new sensor in the mounting hole, and replace the retaining screws and wiring.
A defective camshaft position sensor will set a trouble code that must be cleared. Clear codes with a code reader, and then drive the vehicle through two drive cycles consisting of driving around town in stop-and-go traffic and then a few miles of highway driving. Turn the engine off for a few minutes between cycles; this should enable the readiness monitors. This drive cycle is known as the "relearn procedure," and each manufacturer has its own specific way to accomplish it. The specific relearn procedure for your vehicle can be found at Auto Zone's website (see Resources).
