Symptoms of a Bad Crankshaft Position Sensor
The crankshaft position sensor is a part of the engine management system that monitors the rotations of the crankshaft. This crankshaft rotation speed is used by the car’s built-in computer system to properly make adjustment depending on the requirement to ensure that the car runs at a smooth pace.
Any problem with the crankshaft position sensor can lead to the engine getting damaged which is why it is necessary to fix the issue right away. In this article, we will discuss the common symptoms which will help you figure out whether the crankshaft position sensor is fine or has been damaged.
The function of the Crankshaft Position Sensor
The crankshaft position sensor also called ESS, is located in the engine and detects the rate at which the crankshaft is spinning. The information gathered is passed to the ECU and based on this data, the ECU decides which cylinder should be fired according to the current crankshaft position.
|Bad Crankshaft position sensor||Engine Stalling / Shut off while driving |
Hard Starting condition
Check Engine Light
|Bad crankshaft sensor |
Faulty Trigger Wheel for sensor
Corrosion in connector to sensor
Faulty ECM/PCM (Rare)
|Replace Crankshaft position sensor |
Repair Trigger Wheel
Clean the connector to the sensor
Symptoms of bad or failing Crankshaft Position Sensor
The most common symptoms of a bad or failing crankshaft position sensor are that your vehicle may not start or your engine will stop while driving. You can also experience misfires and a Check engine light flashing on your dashboard. The crankshaft position sensor can fail due to various reasons and its failure results in a number of engine related problems.
Here are some of the common symptoms to help you determine whether or not your car’s crankshaft position sensor is damaged.
Check Engine Light
The check engine light illuminates due to many reasons and one of them is the sensor failure. When the engine is running for a long time, the sensors stop working due to increased heat level causing the check engine light to illuminate. It is recommended to have your car checked by a mechanic to determine the root cause of check engine light.
Loss in Acceleration
If you notice a loss in acceleration at high speed, this is due to a fault crankshaft sensor. What happens is that the engine control unit does not receive correct information due to the faulty sensor which causes a problem while synchronizing the engine pistons together. Moreover, incorrect spark timing and fuel injection adjustment also causes poor acceleration.
Once the crankshaft sensor fails, the crankshaft position cannot be determined. This may cause the engine to vibrate heavily, reducing the engine power and increasing mileage.
Increase in Mileage
Due to the faulty crankshaft position sensor, the spark timing and fuel injection are not carried off effectively causing a disturbance in the engine operations as well as loss in fuel efficiency. If you notice that your car is sipping more than usual gasoline, it may be due to the bad crankshaft position sensor.
Difficulty in Starting the Car
Once the sensor fails, the onboard computer receives a malfunction code which has information regarding the sensor failure. Initially, the car would face difficulty in starting due to improper timing and fuel adjustment and later the car won’t start at all. However, this could also be due to an electrical fault or a bad connection.
Engine misfire occurs when the onboard computer does not receive enough information about the piston position causing the cylinder to misfire. Engine misfire could be due to a faulty crankshaft position sensor or damaged spark plug.
Besides facing issues with acceleration at high speed, if you notice your car’s engine stalls at low speed, then the problem is most likely with the crankshaft sensor as it is responsible for ignition timing.
Diagnosing the Crankshaft Position Sensor
If the check engine light illuminates, it means that the ECU has registered a trouble code. There are many diagnostic codes for various problems and they can be checked using a diagnostic scan tool. If the code lies between P0335 and P0338 it indicates that the problem is with the crankshaft sensor.
This is one of the simplest ways to diagnose a problem with the crankshaft position sensor. However, by the time the check engine light illuminates, there would be a number of other issues affecting the engine as well, which is why it is a good practice to adopt other diagnosing technique as well. If you want to read the trouble codes at home you can do it with an OBD2 scanner from Amazon.
Read the Engine RPM
This technique can also be performed using the diagnostic scan tool. The trick is to read the engine speed in revolution per minute (RPM) and this data is collected from the crankshaft position sensor. Connect the diagnostic scan tool and crank the engine. If the scanner gives a reading between 100 and 500 RPM, then it is working fine. Anything besides that reading indicates a problem with the crankshaft sensor whereas, zero reading suggests that the sensor has failed completely.
Testing Through Multimeter
If you don’t have access to a diagnostic scan tool, you can also test the sensor using a multimeter. A multimeter is used to diagnose electrical components as it reads voltage, current, and resistance.
To check the sensors’ resistance, remove the sensor and attach one end of the multimeter to the wiring lead of the sensor. If the multimeter reads zero resistance, it means that a short circuit has occurred while infinite resistance indicates an open circuit. Either way, it suggests that the sensor is faulty and should be replaced. If you want to find a good multimeter you can check this out on Amazon:
Innova 3340 Automotive Digital Multimeter (10 MegOhm/UL)
Replacing the Crankshaft Position Sensor
Step 1: Remove the battery’s negative terminal to avoid the risk of any electrical shock
Step 2: Locate the Crankshaft Position Sensor. Usually, it is found in front of the engine but the location varies from car to car. Check your vehicle’s manual to know exactly where the sensor is located.
Step 3: Remove the Sensor by carefully detaching the wires then unscrew the bolts using a socket wrench
Step 4: Once the old sensor is removed, install the new one. It is also important that you install new O-rings so that the sensor fits perfectly. Re-connect the wires properly and screw the bolts.
The average cost of replacing the crankshaft position sensor is between $120 and $300. The sensor itself costs between $70 and $120 while the remaining amount is the labor cost. Although replacing the crankshaft position sensor is a simple task but if you’re are not comfortable in replacing it yourself, just take your car to a professional mechanic or auto repair shop.