Bad Crankshaft Position Sensor: Symptoms, Causes, & How to Replace It

The crankshaft is one of the major parts of the engine. It ensures the efficient performance of the engine. It helps to move the vehicle wheels. An internal combustion (IC) engine contains a crankshaft position sensor (CKP) to monitor the speed and position of the crankshaft. The vehicle’s computer (usually PCM) utilizes the data of the crankshaft sensor to control the ignition timing and fuel injection rate. When the crankshaft position sensor goes bad, it produces different symptoms. This article explains the working, function, and signs of a bad crankshaft position sensor.

What is a Crankshaft Position Sensor?

The crankshaft position sensor is an electronic component used in IC engines to track the speed or position of the crankshaft. The powertrain control module (PCM) highly depends on the crankshaft data to manage ignition system timing, fuel injection, and other engine-related variables.

Both petrol engines and diesel engines rely on crank sensor performance for optimal performance.

Crankshaft Position Sensor

Before the invention of the electronic crank sensor, petrol engine distributors needed manual adjustments based on a timing mark.

The crankshaft position sensor works along with a camshaft position sensor to observe the interaction between valves and pistons within the engine. This proper interaction between the valves and pistons is a crucial aspect in engines featuring variable valve timing. This technique is also employed to synchronize a four-stroke engine during startup, informing the management system about the appropriate moment for fuel injection.

Additionally, the CKP sensor is frequently utilized as the primary means of determining engine speed in revolutions per minute (RPM).

Crankshaft Position Sensor Function

The main function of the crankshaft position sensor is to measure the crankshaft position or speed and send this data to the powertrain control module (PCM). The efficient performance of this sensor is essential for optimal vehicle performance.

The PCM of your vehicle utilizes the data of the crank sensor to fine-tune the engine’s timing.

Crankshaft Position Sensor Function

When the sensor malfunctions, the PCM returns to default settings to keep the engine running. However, this can lead to noticeable drivability issues such as engine stalling, misfiring, or poor fuel economy.

On the other hand, if your PCM fails to detect a faulty crankshaft position sensor and continues to receive inaccurate readings, it will optimize performance based on incorrect data. This issue may cause further damage and result in costly repairs.

Bad Crankshaft Position Sensor Symptoms

As the crankshaft position sensor goes bad, it gives one of the below-given signs:

  1. Illuminated check engine light
  2. Excessive engine vibrations
  3. Hard starting
  4. Poor engine performance
  5. Engine misfire
  6. Poor fuel economy
  7. Engine stalling
  8. Car jerking
  9. Rough idle

1) Illuminated Check Engine Light

The illuminated check engine light is the first sign of a faulty crankshaft position sensor.

The powertrain control module (PCM) continuously communicates with the crankshaft position sensor to control different features of the engine. When the sensor goes bad, it sends inaccurate data about the crankshaft’s speed and position to the PCM.

check engine light

When the PCM receives wrong information from the CKP sensor, it triggers the check engine warning light on the dashboard to alert the driver. Your PCM may also trigger the trouble codes P0335 or P0336 along with the check engine light.

Read More: Causes of Check Engine Light Illumination 

2) Excessive Engine Vibrations

An engine with a malfunctioning crankshaft position sensor doesn’t operate at peak performance. The powertrain control module (PCM) of the vehicle uses the data of the crank sensor to regulate the ignition timing and many other features.

Engine Vibration due to bad crankshaft position sensor

If your PCM uses incorrect readings from the crankshaft sensor to determine fuel and ignition timing, it may lead to a bumpy driving experience.

If the PCM fails to time these processes correctly for a long time, the issue will only worsen until it is resolved, potentially causing further damage.

3) Hard Starting

When a faulty crankshaft position sensor is severely out of sync, you may struggle to start your car or keep it running. This issue typically arises when the problem has persisted for a long time, potentially indicating other underlying issues.

Hard Starting condition

However, if your check engine light is on and the PCM has defaulted to predetermined values, this might not be an immediate concern.

Instead, this issue usually arises when the crankshaft position sensor provides inaccurate readings, and the PCM fails to detect it.

4) Poor Engine Performance

As we discussed above, engine performance highly depends on the performance of the crankshaft sensor. Poor engine performance is one of the clear symptoms of a faulty crankshaft position sensor.

Poor Engine Performance

When this sensor goes bad, it significantly impacts the PCM’s ability to maintain proper fuel injection rate and ignition timing. As a result, you may experience a hesitation when pressing the gas pedal harder, or the engine might not respond at all. This may be particularly hazardous on roads where quick acceleration is necessary.

Read More: Bad Accelerator Pedal Symptoms and Causes

5) Engine Misfire

A faulty crankshaft position sensor may also cause misfiring. This issue occurs when a faulty crank sensor sends wrong information about the piston position to the PCM, which in turn results leads to misfires within one or more of the combustion chambers.

engine Misfiring, symptoms of bad crankshaft position sensor

However, your car may misfire due to many other issues. However, a bad spark plug can also cause this issue. Therefore, it is important not to dismiss the possibility of a faulty crankshaft position sensor if you’re experiencing other related symptoms.

6) Poor Fuel Economy

As we discussed above, the main function of the crankshaft position sensor is to measure the crankshaft position and send this data to the PCM. The PCM utilizes this data to adjust fuel injection rate, and ignition timing, ensuring optimal engine performance and efficiency.

Poor fuel economy

When the crankshaft sensor becomes faulty, it starts sending wrong information to PCM. When the PCM receives wrong information, it may be unable to efficiently regulate the fuel injection rate, resulting in a lean or rich air-fuel mixture.

The poor air-fuel mixture leads to poor combustion and your engine works hard to properly combust the mixture. As a result, your engine starts to consume more fuel than normal.

7) Engine Stalling

Frequent engine stalling can occur when driving with a bad crankshaft position sensor. If this issue is left unaddressed, your engine may eventually stop functioning altogether.

engine Stalling, symptoms of bad crankshaft position sensor

Your vehicle engine may stall due to many other reasons, such as a faulty fuel injector or faulty camshaft sensor. Therefore, when your engine stalls, properly inspect all the parts to find the root cause of the engine.

Read More: Engine Stalling Causes and Preventions

8) Car Jerking

A faulty crankshaft position sensor may lead to the car jerking while driving. When the sensor goes bad, the PCM will be unable to properly control the ignition timing and fuel injection. This leads to hesitation or sudden variations in engine speed, which may cause the vehicle to jerk.

vehicle Jerking

9) Rough Idle

A faulty crankshaft sensor may lead to a rough idle. The crankshaft position sensor is one of the major components of the engine management system. When it becomes faulty, it may lead to poor combustion of the air-fuel mixture in the combustion chamber, which causes a rough idle.

Rough Idling due to a faulty crankshaft sensor

Causes of a Bad Crankshaft Position Sensor

  • Age and wear: With time, the crankshaft position sensor may degrade or wear out because of constant exposure to extreme pressure, vibration, heat, and other harsh operating environments. These harsh operating conditions may lead to the failure of the sensor.
  • Physical Damage: Accidental damage to the sensor or its casing during car repairs or maintenance may also lead to its failure.
  • Moisture or Corrosion: The internal parts of the sensor may damage due to corrosion or moisture.
  • Damage from heat: Extreme heat for a long time may damage the internal parts of the camshaft position sensor. A high temperature may force the internal parts to expand, while a low temperature may cause brittleness or cracking.
  • Contaminants: The contaminants such as debris or oil may gather inside the sensor, which affects its capability to accurately measure the crankshaft position. This may lead to erratic readings and poor performance.
  • Manufacturing Material: The manufacturing material of the sensor plays a vital role in its efficient performance. A sensor made of poor material can’t work efficiently for a long time.

Read More: Bad Camshaft Sensor Symptoms and Causes

How To Make a Temporary Fix for Crankshaft Position Sensor?

To temporarily fix a bad crankshaft position sensor, you may use one of the below-given methods:

  • Restart the Engine
  • Add More Fuel
  • Add More Engine oil
  • Start the vehicle in neutral
  • Disconnect the CKP Sensor

1) Restart the Engine

If you’re driving and your car begins to jerk and shake or the check engine light comes on, it’s best to pull over to the curb immediately. To restart the engine, follow the below-given steps:

  • Stop the vehicle on a side
  • Turn off the engine
  • Wait for a few minutes to let cool down the engine before restarting in order to minimize further jerk to your vehicle

2) Add More Fuel

If your car suddenly stops due to the PCM not providing adequate fuel to the engine cylinders, you can resolve the issue by refueling your vehicle.

3) Add More Engine oil

If the engine oil level is less than a specified limit, this could be the source of the issue. Try to restart the engine after adding more oil. 

Read More: Low Engine Oil Symptoms and Causes

4) Start the vehicle in neutral

If there is a fault with the transmission, try to start the vehicle in neutral mode. In this way, your vehicle will start.

5) Disconnect the CKP Sensor

If your car fails to start initially, you should retry by disconnecting the crankshaft sensor.

  • First, locate the CKP sensor. Check your manufacturer’s manual to find the sensor.
  • Next, disconnect the battery negative terminal and the sensor connector.
  • Now, try to restart the car. With some luck, the car will start using its default mapping.

If the car still doesn’t start, consider seeking professional assistance to replace the CKP sensor in your vehicle.

Crankshaft Position Sensor Location

The location of the crankshaft position sensor depends on the vehicle model and the type of engine. The crankshaft position sensor is usually located near the bottom of the engine, close to the crankshaft itself. This placement is logical, as the sensor’s primary function is to measure the crankshaft’s position.

Crankshaft Position Sensor Location

To locate the crankshaft sensor, direct your attention toward the bottom of the engine, typically on one of its sides. Due to its deep-seated position within the engine, the sensor is challenging to find, and replacing or removing a bad one can be even more difficult.

How to replace a Crankshaft Position Sensor

  • To replace a faulty crankshaft position sensor on your own, gather some essential tools such as a new crankshaft sensor, jack stands, cleaning solution, a ratchet and socket set, and a floor jack.
  • Park your vehicle in a safe place.
  • Lift the vehicle with the help of a jack and put jack stands underneath it.
  • Disconnect the negative terminal of the vehicle’s battery to prevent any electrical issues while working on the vehicle.
  • Locate the crankshaft sensor, which can be found near the timing cover or harmonic balancer of your engine. You can also consult your vehicle manufacturer’s manual to easily locate the crank sensor.
  • Disconnect all the connectors and wires connected to the sensor. After removing the mounting bolts, gently remove the sensor from its mount.
  • Clean the area surrounding the sensor mount to ensure a proper seal when installing the new sensor.
  • Properly lubricate the O-ring on the replacement sensor for easy installation.
  • Place the new sensor into the mount and secure it with the mounting bolts.
  • Reinstall all other parts back in their original places.
  • Reconnect the negative terminal of the battery.
  • Turn on the engine to test the newly installed sensor. If your engine starts immediately, it means you have successfully installed the crankshaft sensor.
  • If the car fails to start, there may be another problem that requires attention.

Crankshaft Position Sensor Replacement Cost

If you experience one or more of the above symptoms, then you may have a faulty crankshaft position sensor. The replacement cost of the crankshaft position sensor varies according to your vehicle model, engine type, and type of part brand.

The average replacement cost of the crankshaft position sensor is between $110 and $320. In this cost, the cost of the part itself is between $7o and $140. The cost of the labor is from $40 to $180.

FAQ Section

What is a Crankshaft Position Sensor?

The crankshaft position sensor is an engine sensor that is used to track the speed or position of the crankshaft

What causes the crankshaft sensor to go bad?

There are a few things that can cause the crankshaft position sensor to fail, including damage, debris, and faulty circuitry.

The excessive build-up of heat in the engine can lead to crankshaft sensor damage by melting the plastic covering—circuitry Problems. A faulty voltage or loose, worn-out, or damaged wiring can disrupt the signals sent to and from the crankshaft sensor, causing it to have issues.

What are the signs of a bad crankshaft shaft position sensor?

As the crankshaft position sensor goes bad, it gives one of the below-given signs:

  1. Engine Stalling
  2. Poor Engine Performance
  3. Engine Misfiring
  4. Trouble Starting Car
  5. Excessive Engine Vibrations
  6. Check Engine Light turns On

How long do crankshaft position sensors last?

The lifespan of a crankshaft sensor cannot be determined precisely, as it is influenced by various factors, including sensor quality, driving conditions, and the overall maintenance of the car. These sensors are usually designed to endure the entire lifetime of a car and should only be replaced if they become faulty.

What happens when a crank sensor goes out?

If your crankshaft sensor is not working properly, the motor control unit in your vehicle won’t be able to execute the changes to the fuel injection or to the spark timing whenever the engine speed climbs.

Can I start my car without a crankshaft position sensor?

A faulty crankshaft sensor may prevent the engine from starting because the spark plugs don’t know when to fire. But if the vehicle has a camshaft position sensor, your PCM may utilize the data of these sensors as an alternative to the crankshaft sensor, allowing the engine to run even without it.

Can I rest the crankshaft sensor by disconnecting the battery?

The crankshaft position sensor is used to monitor the crankshaft’s position. Disconnecting the battery will not reset the sensor, as it does not store any data that requires resetting. For most car models, an OBD-II scanner is needed to clear any trouble codes within the PCM.

What does a bad crankshaft sound like?

A faulty crankshaft itself doesn’t generate a specific sound. However, if it is bad, it may produce different engine ignition timing, which may lead to unusual noises such as rattling, tapping, or knocking coming from the engine. These noises are usually produced because of poor combustion of air-fuel mixture and are not directly caused by the sensor.

Can a bad crankshaft position sensor cause a misfire?

Yes, a faulty crankshaft position sensor may lead to misfires. It is responsible for providing the powertrain control module (PCM) with the crankshaft’s position and timing information, which is important for precise fuel ignition and delivery. When the sensor becomes bad, it may lead to wrong ignition timing, leading to misfires and poor engine performance.

Is driving without a crankshaft sensor serious?

Yes, driving without a functioning crankshaft sensor is very dangerous because it may cause various drivability issues, such as poor fuel economy, stalling, poor engine performance, or even an entire engine shutdown. This sensor is important to determine the perceived ignition timing and fuel injection rate. Without this sensor, your engine will be unable to run smoothly or may not start at all.

Can a bad crank sensor cause a loss of power?

Yes, a bad crank position sensor may lead to poor engine performance and power loss. This sensor has the responsibility to provide the crankshaft’s correct position and timing information, which are most important for fuel injection and ignition. A bad sensor may cause poor engine timing, resulting in poor performance, hesitation, or even stalling.

Read More

Leave a Comment