Crankshaft Position Sensor

All of the parts in a car’s engine have to operate together like clockwork for it to run, and an engine management system ensures monitors it all. A crankshaft position sensor serves a pivotal role for an engine, otherwise it wouldn’t start at all. Often called simply a crank sensor, it measures how fast the crankshaft is rotating and reports that information back to the onboard computer.

How Do Crankshaft Position Sensors Work?

You’ll find a crankshaft position sensor on every internal combustion engine but the location isn’t always the same. On some cars, it’s at the front next to the main crankshaft pulley while on others the crankshaft position sensor is on the transmission bell housing or pointed into the cylinder block.

A crankshaft position sensor is made up of a hard plastic housing and a sensor head where the magic happens. Modern cars use a three-wire Hall sensor that creates a magnetic field while older cars sometimes use a two-wire pick-up coil. They serve the same function, just using different tech.

Regardless of where the crank sensor is positioned, its purpose is to measure rotational speed. The sensor head is near a reluctor ring that has a reference point in it such as a missing tooth that correlates with top-dead center on cylinder #1. When the ring is rotating, the sensor detects the reference point and produces a pulsed voltage signal. That signal is sent to the onboard computer that can perform its functions based on its data and that from camshaft position sensors and other information.

Signs of a Bad Crankshaft Position Sensor

If the crankshaft position sensor isn’t working as it should, there will certainly be signs that something is wrong and needs your immediate attention. Because it’s crucial for the powertrain control module’s timing reference, the engine won’t run properly if the data is missing or incorrect. You might notice acceleration issues, a rough-running engine, or poor fuel mileage since the computer doesn’t know how to adjust the timing. The engine might stall or it may not even start in the first place.

One of the crankshaft position sensor symptoms that’s all but guaranteed is an illuminated Check Engine Light, and it might even be flashing due to the seriousness of the issue. DTCs between P0335 and P0338 indicate a crankshaft position sensor issue, although a more thorough checkup is required to be sure that’s the true problem.

Replacing a Crankshaft Position Sensor

You won’t usually need special tools or fancy equipment to change the crank sensor, but you might need it for the diagnosis and testing beforehand. Once you’ve confirmed it’s the problem, changing it out is straightforward like most other automotive sensors. The part ranges from around $40 to $150 or more depending on your vehicle.

At AutoZone, find the right crankshaft sensor for your vehicle when you use the filter above using the year, make, model, and engine size. An AutoZoner at one of our locations near you can help find you the right part as well. Get your parts fast with our Free In-Store or Curbside Pickup, or select Free Next-Day Delivery to have it sent straight to you.