What Are The Symptoms Of A Bad Crankshaft Sensor?

Brandon Trenton

Bad Crankshaft Sensor Symptoms

All modern-day vehicles have a crankshaft sensor that monitors the speed and rotational position of the vehicle’s crankshaft. The engine control unit receives reports from the sensor, that allows it to make adjustments for compensating any malfunctions. If the sensor fails, the reports may not be sent, and if they are sent the information contained may be inaccurate.

Your vehicle’s engine may experience long term damage or prevent it from working. Identifying early symptoms of the sensor will reduce the risk of malfunctions leading to expensive repairs or worse, complete engine shutdown.

Common Symptoms of a Bad Crankshaft Sensor

Two key parameters used by a vehicle’s computer for engine management calculations are the crankshaft position and speed. If the sensor doesn’t work correctly, all these calculations will be incorrect. Engine damage can be minimized if one understands the symptoms of a bad crankshaft sensor.

1. Check if the Engine Light is On

The engine light may turn on due to several reasons, of which problems with the crankshaft sensor is also one reason. One common issue is that of overheating. Int hat case, turning the engine off and letting it cool down will cool down the sensor as well. If the check engine light remains off when the vehicle is restarted, you have solved the problem most likely. Otherwise, you may need to get the services of a mechanic to check your vehicle’s computer closely.

2. Engine Vibrations

The crankshaft’s position is not monitored by the sensor, once it fails. This may lead to heavy engine vibrations and this juddering can affect the power produced by the engine over time, along with its ability to record mileage accurately. These effects can be reduced by being aware of how do the normal vibrations of your car feel like so you can take action immediately if you feel anything different.

3. Accelerator Response

If your vehicle has a slower than normal accelerator response rate, it is a sign of a bad crankshaft sensor. Correct cylinder position information will not be sent to the vehicle’s computer if the crankshaft sensor isn’t working, which increases the time between computer receiving and applying data, which causes the accelerator to hesitate instead of giving a real-time response during driving.

4. Erratic Start Up

If your vehicle is unable to start constantly, there may be a serious issue with its crankshaft sensor. This is among the most serious symptoms of a bad crankshaft sensor, and the problem may even escalate without any warning further, leaving the vehicle halted altogether. The same symptoms may be caused by circuit issues and loose electrical connections.

5. Cylinder Misfiring

If the crankshaft sensor is failing, it can not provide correct piston position information to the vehicle’s computer. One of the cylinders is caused to misfire as a result. Cylinder misfiring may also be caused due to issues with spark plugs, however, if you experience misfiring even after dealing with spark plug issue, the crankshaft sensor is most likely causing the problem.

6. Backfiring and Stalling

If your vehicle starts and runs without any obvious issues, yet the engine turns off after running just for a while, this may be a sign of crankshaft sensor malfunction. Stalling and backfiring is a symptom of a bad crankshaft sensor. This may seem like a simple annoyance only but can cause pressing issues further, including the engine shut down permanently as well.

Testing a Crankshaft Position Sensor

If any of these symptoms are observed in your vehicle, it is high time you check the sensor if it is causing these issues. There are multiple steps you may take to test the sensor before going up to the mechanic.

Voltage output test:

Once the voltage output has been tested, the readings can be compared with specifications present in your handbook. This is an easy and clear way to see if the crankshaft sensor has malfunctioned.

Voltmeter wiring:

The wiring present at the sensor connector may be back probed if the voltmeter has needle probes.

Setting the multimeter:

Set your digital multimeter to AC millivolts range and start the engine to check if the reading is against the manufacturer’s specifications. If the resistance value is given in the vehicle manual, the sensor can be checked without cranking the engine. 

Replace the Crankshaft Sensor

If you are confident enough about your mechanical abilities, there is a chance you can replace the crankshaft sensor on your own. However, if you are not sure and do not have the right tools or space required, it is better to leave it on an expert mechanic. Either way, you should have knowledge of the basic steps:

  • Disconnect the battery, beginning with its negative terminal
  • Keep your workspace ready, you will need a jack to fit under your vehicle and reach the sensor. Make sure the position of your vehicle is secure.
  • Disconnect the electric connector, starting by releasing its plastic clip and pulling the connector lose carefully. You may have to wiggle it side to side in order to loosen it up. Check if the connector has rust. If your vehicle engine stalls, rusting may be a cause. Clean or replace the pigtail as required.
  • Now remove the mounting bolts of the sensor, which are generally one or two bolts measuring 10mm, holding the sensor in one place.
  • Remove the sensor now, if it is stuck then remove it firmly yet gently by twisting and pulling to loosen it up. If this doesn’t work, a door panel clip removal tool may prove to be useful for prying it out. Make sure you aren’t applying a lot of pressure as the sensor can break in that case.
  • Once the old sensor is removed, you now need to prepare the new one. Begin with lubricating the o-ring lightly which will make it easier to fit in one place.
  • Before you position the new sensor and push it in place firmly, make sure to clean the position sensor porthole.
  • Now replace the mounting bolts and tighten them up.
  • Connect the electrical connector again and make sure its clip is engaged completely.
  • Any other parts removed to access the sensor should also be replaced, followed by lowering down the vehicle carefully.
  • Connect your battery again, beginning with the positive terminal now. You are all set to test the new sensor and go back to driving trouble-free.

Taking good care of your vehicle and observing small changes in how it is operating are the best ways that ensure excellent performance along with fuel efficiency. The crankshaft sensor is just one of the many sensors present in your vehicle, designed to enhance its performance. Ignoring bad crankshaft sensor’s symptoms may lead to many issues that could have been avoided otherwise.