2016 Mercedes-Benz S550e Crankshaft Position Sensor Replacement Cost

As the crankshaft spins, the position sensor magnetically reads its position. This information is constantly sent to the engine's computer for comparison with data from the camshaft position sensor. When the two signals reach the computer, they must match; otherwise, the computer will think there is a mechanical error in the engine and will adjust some settings in response.

When the computer senses the engine is out of time, it will turn on the check engine light, and the engine may start and stall, or fail to start at all. If the engine runs, it will run poorly, and get bad fuel mileage. » LEARN MORE: Symptoms of a bad crankshaft position sensor

Driving a vehicle with a failed camshaft or crankshaft position sensor is usually impossible. If driving is possible, it is not recommended. If the sensor is functioning normally and reporting an error, the engine may be out of time or may have suffered a mechanical failure.

There's no set replacement interval for the crankshaft position sensor, and on many cars, the part will last the lifetime of the vehicle. It's not uncommon for it to fail, however, and the likelihood increases once you pass 100,000 miles.

Using a professional-grade scanner, a mechanic can read where the sensors think the crankshaft and camshaft are, and compare this to their actual position. If the reading from either sensor is incorrect, the sensor will be tested and replaced if necessary.

To replace the crankshaft position sensor, you have to disconnect any electrical connectors and then unscrew the sensor. Sealant may be applied before inserting the new sensor into the engine. On some vehicles, the crankshaft position sensor is located inside the engine block, and significant deconstruction is required to get to it. In these cases, we recommend trusting a professional technician with the repair.

Make sure to use high-quality, OEM sensors. Lesser products will likely cause a repeated repair. When checking this sensor, the vehicle's timing belt should be inspected as well. If the timing belt or timing chain has failed, it should be replaced and the engine should be further inspected.

Replacing this sensor is easy enough — but what's often tricky is getting the correct diagnosis. Unless you have the proper scanning tools and knowledge, it's likely best to let a professional technician handle this diagnosis and repair.