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How to Replace a Crankshaft Position Sensor?

Author: Apogeeweb
Date: 27 Aug 2021
 1081
How a Crankshaft Position Sensor Works

Ⅰ What is a Crankshaft Position Sensor

Ⅱ Function and Location of Crankshaft Position Sensors

Ⅲ How does a Crankshaft Position Sensor Work

Ⅳ Symptoms of a Bad Crankshaft Position Sensor

4.1 Engine Vibrations

4.2 Check Engine Light

4.3 Weak Engine Performance

4.4 Trouble Starting Car

4.5 Engine Stalling

4.6 Cylinder Misfiring

Ⅴ How to Replace a Crankshaft Position Sensor

Ⅵ Frequently Asked Questions about Crankshaft Position Sensor

 

Ⅰ What is a Crankshaft Position Sensor

The engine, together with its components such as the crankshaft position sensor, is one of the most critical aspects of your car. Internal combustion engines are found in almost all modern cars. The crankshaft position sensor is responsible for keeping track of the engine's many moving parts, such as the crankshaft, valves, and pistons. It keeps track of the crankshaft's position and rotational speed, sending the data to the engine management unit so it can make modifications based on operating conditions.

 

Engine management systems employ this information to govern fuel injection, ignition system timing, and other engine characteristics. On petrol engines, the distributor had to be manually set to a timing mark before electronic crank sensors were available.

 

Video. Crankshaft Position Sensor Testing and Replacement

 

Ⅱ Function and Location of Crankshaft Position Sensors

The crankshaft position sensor's primary function is to determine the crank's position or rotational speed (RPM). The information sent by the sensor is used by Engine Control Units to control factors like ignition and fuel injection timing. The sensor will control the fuel injection in a diesel engine. The sensor output may also be linked to other sensor data, such as the cam position, to determine the current combustion cycle, which is critical for a four-stroke engine's beginning.

 

Location of Crankshaft Position Sensor

Figure1. Location of Crankshaft Position Sensor

 

The crankshaft position sensor can be found in different places depending on the vehicle. It needs to be close to the crankshaft, therefore it's usually found on the engine's front underbelly. The timing cover is often where you'll find it mounted. It may be positioned on the engine's back or side. The clutch flywheel speed is sometimes used to determine the crankshaft speed using the crankshaft position sensor. The sensor is attached to the transmission's bell housing in these circumstances.

 

Ⅲ How does a Crankshaft Position Sensor Work

The teeth on the reduction ring attached to the crankshaft pass near to the sensor tip on the crankshaft position sensor. One or more teeth are missing from the reduction ring, which serves as a reference point for the engine computer (PCM).

 

The sensor generates a pulsed voltage signal when the crankshaft spins, with each pulse corresponding to a tooth on the reduction ring. With the engine idling, the photo below displays the actual signal from the crankshaft position sensor. As you can see from the graph, the reduction ring in this vehicle has two missing teeth.

 

How a Crankshaft Position Sensor Works

Figure2. How a Crankshaft Position Sensor Works

 

The PCM uses the signal from the crankshaft position sensor to determine when and in which cylinder to fire the spark. The signal from the crankshaft position is also utilized to check for misfires in any of the cylinders. There will be no spark and the fuel injectors will not operate if the sensor signal is missing.

 

Magnetic sensors with a pick-up coil that produce A/C voltage and Hall-effect sensors that produce a digital square wave signal, as shown in the photo above, are the two most prevalent varieties. Hall-effect sensors are used in modern automobiles. A two-pin connector is found on a pick-up coil sensor. A three-pin connector is used to connect the Hall-effect sensor (reference voltage, ground, and signal).

 

Crankshaft position sensor signal

Figure3. Crankshaft position sensor signal

 

Ⅳ Symptoms of a Bad Crankshaft Position Sensor

Crankshaft speed and position are critical elements in engine management calculations, and many engines will not start if the crankshaft position sensor does not provide an accurate signal. A malfunctioning crankshaft position sensor usually causes a few symptoms that alert the driver to a potential problem that needs to be addressed.

 

4.1 Engine Vibrations

 

Engine Vibrations

Figure4. Engine Vibrations

 

Vibrations originating from the engine are another indicator of a malfunctioning crankshaft position sensor. Some people believe that when the engine is running, there is always some vibration emanating from under the hood. If you observe a significant increase in vibration, it could be due to an issue with the crankshaft position sensor.

 

This vibration is frequently accompanied by a significant reduction in fuel economy and power. To get where you need to go, you'll need a lot more power and gas.

 

4.2 Check Engine Light

 

Check Engine Light

Figure5. Check Engine Light

 

The crankshaft position sensor is constantly communicated with by the engine control unit. If there is ever a problem with the sensor, the computer will receive incorrect information about the crankshaft's speed and location.

 

This will cause engine malfunctions, resulting in the Check Engine warning light on the dashboard turning on. One of the first signs of a malfunctioning crankshaft position sensor should be this. P0335 is a typical error code that may appear.

 

4.3 Weak Engine Performance

 

Weak Engine Performance

Figure6. Weak Engine Performance

 

Your engine control unit will not know the right position of the crankshaft or cylinders if the crankshaft position sensor is damaged. This will cause the control unit's ability to maintain the engine's functioning and performance to be delayed.

 

During this time, there will be moments of hesitancy every time you press harder on the gas pedal. It may or may not respond at all. On a road where you must move quicker without hesitating, this can be quite risky.

 

4.4 Trouble Starting Car

 

Trouble Starting Car

Figure7. Trouble Starting Car

 

Another major warning flag is that you are having trouble starting your vehicle. When you try to start your car, the crankshaft position sensor immediately starts measuring the crankshaft's position and speed. It receives a specific malfunction code from the sensor, indicating that there is an issue with its operation.

 

When you try to start your vehicle while this problem is present, the engine will be more difficult to start. You may not be able to start your engine at all if the problem persists.

 

4.5 Engine Stalling

 

Engine Stalling

Figure8. Engine Stalling

 

One day, you may be cruising along when your engine suddenly stops running. When you have a defective crankshaft position sensor, this is known as engine stalling, and it can happen very frequently.

 

If this sensor is not replaced soon, your engine will eventually stop working. You'll have no choice but to have your car towed to a repair to have the sensor changed.

 

4.6 Cylinder Misfiring

 

Cylinder Misfiring

Figure9. Cylinder Misfiring

 

If the crankshaft position sensor fails, the engine control unit will not be able to reliably communicate data about the piston position. A misfire in one or more of the chamber cylinders is common as a result of this.

 

A faulty spark plug can also cause this, but if you're experiencing any of these additional symptoms, don't discount out a bad crankshaft position sensor.

 

Ⅴ How to Replace a Crankshaft Position Sensor

Start by looking for the sensor, which you can do by inspecting the engine and looking for any sensor that matches the new sensor you just bought at the lower level.

 

Materials:

  1. shop light
  2. carburetor cleaner
  3. plastic clip
  4. cleaner

 

Tools:

  1. small wrench or socket
  2. small pick or standard screwdriver

 

Step1 Disconnect the Battery

It's a good idea to disconnect the battery whenever you're working on the engine's inner workings to avoid a short circuit in the car's electrical system. Remove the disarm plug for the main battery pack on hybrid vehicles as well. The location can be found in your owner's manual.

 

Disconnect the Battery

Figure10. Disconnect the Battery

 

Step2 Clear Access to the Sensor

This crank sensor is located behind the starter motor, which must be removed to access the sensor. When working beneath the car, use a shop light to see what you're doing.

 

Clear Access to the Sensor

Figure11. Clear Access to the Sensor

 

Step3 Inspect the Sensor Location

Because of the transmission cooling lines, this sensor is difficult to notice, although it is located on the side of the block with the electrical connector attached. If the crankshaft angle sensor is oily, this is a good opportunity to clean it out with a small bit of carburetor cleaner to get a fresh start on the work.

 

Inspect the Sensor Location

Figure12. Inspect the Sensor Location

 

Step4 Release the Electrical Connector

A plastic clip will hold an electrical hookup to the sensor, which you must push down or pull outward to disengage. Wiggle the connector away from the sensor gently once this is done. This connector can become stuck due to the weather pack seal, which helps keep water out of the sensor terminals, causing corrosion. After removing the connector, inspect it for rust and clean or replace the pigtail if necessary. The engine will stall due to this issue alone.

 

Release the Electrical Connector

Figure13. Release the Electrical Connector

 

Step5 Remove the Sensor Mount Bolt

The majority of crankshaft sensors only have one mounting bolt, which is usually a 10mm bolt. Remove the bolt with a tiny wrench or socket by rotating it counterclockwise and storing it to the side.

 

Remove the Sensor Mount Bolt

Figure14. Remove the Sensor Mount Bolt

 

Step6 Remove the Sensor

Because the crank sensor has a long stem that can get jammed in the block, removing it can be difficult. To push the sensor mounting tab away, insert a small pick or a regular screwdriver beneath it. Applying too much pressure on these sensors can lead them to break, leaving a piece of the sensor inside the block. When this happens, you can either press the broken piece inward so it falls into the oil pan and stays there, or you can remove the oil pan and remove the broken piece.

 

Remove the Sensor

Figure15. Remove the Sensor

Once the sensor is free, take a firm grip on it and twist it away from the engine block. On the sensor, there will be a sealing O ring that will need to be replaced with the new sensor. A new O ring is included with most new sensors.

 

Old Crankshaft Position Sensor

Figure16. Old Crankshaft Position Sensor

 

Step7 Match the New Crankshaft Sensor

Wipe away any grease from the old sensor so you can notice any design differences in the new sensor. When installing new sensors, such as mounting tabs, minor design adjustments are common. The length of the sensor stem can be variable because if it is too long, it will contact the crankshaft, and if it is too short, it will not read accurately.

 

Match the New Crankshaft Sensor

Figure17 .Match the New Crankshaft Sensor

 

Step8 Installing the New Crank Position Sensor

Clean the position sensor porthole with a shop towel before inserting the new sensor to ensure a proper seal to the new sensor O ring. Because there will be motor oil in this port, do not spray carburetor cleaning within it. To help with the cleaning, spray cleaner on the shop towel.

 

Sensor Port

Figure18. Sensor Port

 

Place the new crank sensor in the sensor port hole squarely and firmly while matching the mounting plate hole with the threaded bolt hole in the block. Then, by hand, thread in the mounting bolt by turning it clockwise to avoid cross-threading. To avoid damaging the O ring seal and causing an oil leak, lube it with a tiny amount of clean engine oil or WD40. Thread the mounting bolt into place once the sensor has been placed and tighten to around 2-3 foot-pounds.

 

Install New Cranks Angle Sensor

Figure19. Install New Cranks Angle Sensor

 

Push the electrical connector into position while listening for a click to indicate that it has been properly placed and is ready to use.

Figure .Install Crankshaft Angle Sensor Connector

 

Step9 Reconnect the Battery

When you're done, take the car off the jack stands and rejoin the negative battery cable, and you're ready to go.

 

Reconnect the Battery

Figure20. Reconnect the Battery

 

Ⅵ Frequently Asked Questions about Crankshaft Position Sensor

  1. How much does it cost to replace a crankshaft position sensor?

The average cost for crankshaft position sensor replacement is between $178 and $226. Labor costs are estimated between $98 and $123 while parts are priced between $81 and $103.

 

  1. How long does it take to replace crankshaft sensor?

The engine still may run poorly, either way find a good mechanic, one who specializes in engine performance, and set an appointment – the sooner the better. In most instances, this repair should take no longer than one day.

 

  1. Does a crankshaft sensor have to be programmed?

No, they do not have to be programmed. After the replacement you should cancel the code and see if it comes back.

 

  1. What happens if you don't relearn crankshaft position sensor?

Failure to do such will result in over revving of the engine, causing possible engine damage. 8. Once the engine has returned to idle, check the status of Diagnostic trouble code P1336. If the scanner indicates that the CASE has been learned, the relearn procedure is now complete.

 

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