A failing camshaft position sensor (CMP sensor) can produce a confusing range of problems, depending on the way it fails and the model of the car. On some vehicles, a failing camshaft sensor may lock the transmission in a single gear until you turn off and restart the engine. This cycle may repeat intermittently. If the sensor begins to fail while your car is moving, you may feel the car jerking while losing power. You may also experience a noticeable loss of engine power. For example, the engine can't accelerate above 35mph or the engine may stall intermittently. On some car models, a failed CMP sensor will prevent the ignition from sparking, resulting in the engine not being able to start. Replacing the camshaft position sensor is a relatively easy task that can be performed at home with minimal tools that only requires removing the battery’s negative terminal, the sensor’s electrical cable and mounting bolts. If you are unsure about any DIY repair, it is a good idea to consult a qualified mechanic.