How to Replace a Cam Position Sensor on a BMW

Updated February 21, 2017

BMW engines use a camshaft position sensor, or “CPK,” to note the speed at which the camshaft rotates in relation to the crankshaft. The CPK also monitors the pistons and the engine’s valves. When the sensor fails, the engine will not start. The camshaft position sensor is located at the front of the engine on the passenger’s side cylinder head.

Remove the upper half of the air box, located on the passenger’s side of the front of the engine, which contains the air filter. At the front of the box is a small wire, which powers the temperature sender. Pull the wire away from the box to disconnect it. Disengage the two clips that secure the air intake tube to the right side of the air box by pulling the clips off of the box. Disengage the four clips securing the top of the air box to the lower half of the air box, then lift the upper half of the air box out of the engine compartment.

Remove the air intake hose to access the camshaft position sensor. At the top of the left side of the air intake hose is the mass air flow sensor. Pull the wire at the top of the sensor off the sensor. The idle control valve is a plastic fitting on the right side of the air intake hose. Unplug the valve from the hose. Finally, a single hose clamp attaches the right end of the air intake hose to the throttle body. Loosen the clamp with a screwdriver, then pull the intake hose off of the throttle body.

Remove the camshaft position sensor, located on the side of the cylinder head, just to the left of the red-handled dipstick. Remove the bolt securing the sensor in place with an Allen wrench, then pull the sensor out of the cylinder head. Trace the single wire attached to the sensor to an electrical connection fitting. Squeeze the clip located on each side of the fitting, then pull the two connection fittings apart to free the sensor.

Apply a small amount of engine oil to the rubber washer provided with the replacement camshaft sensor, then position the washer onto the back of the sensor. Slide the new sensor into the cylinder head, then tighten the sensor’s retaining bolt with an Allen wrench. Plug the wire leading from the sensor into its electrical connection plug until it clicks into place.

Insert the tip of the throttle body into the right side of the air intake hose, then tighten the clamp with a flathead screwdriver. Press the idle control valve into the plastic fitting on the right side of the air intake hose. Plug the electrical connection on the mass air flow sensor into the fitting on the left side of the intake hose.

Install the upper half of the air box. Slide the air intake hose onto the large plastic fitting on the right side of the air box, then push each of the two clips from the box onto the intake hose until the clips snap into place. Push the four clips that secure the top of the air box to the lower half of the air box onto the upper half of the box until they snap into place. Plug the electrical connection at the tip of the temperature sending unit into the front of the air box.

Things You'll Need

  • Flathead screwdriver
  • Allen wrench
  • Oil
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About the Author

John Stevens has been a writer for various websites since 2008. He holds an Associate of Science in administration of justice from Riverside Community College, a Bachelor of Arts in criminal justice from California State University, San Bernardino, and a Juris Doctor from Whittier Law School. Stevens is a lawyer and licensed real-estate broker.