How to Replace a Crankshaft Position Sensor?

14th Aug 2024

Is your car struggling to start or experiencing sudden engine stalling? These issues could be signs of a faulty crankshaft position sensor. This sensor plays a crucial role in monitoring the position and rotational speed of the crankshaft, which is essential for your engine's timing and operation.

If your crankshaft position sensor malfunctions, with some basic tools and a bit of patience, you can perform a DIY crankshaft position sensor replacement, avoiding the high costs of a professional mechanic.

In this blog, we will walk through the steps to replace a crankshaft sensor effectively. Whether you're a seasoned DIYer or a first-timer, our straightforward instructions will help ensure you get the job done correctly and safely.

What is a crankshaft position sensor?

The crankshaft position sensor is an essential component in modern vehicles, primarily responsible for monitoring the precise position and rotational speed of the crankshaft. This data is critical because it allows the engine control unit (ECU) to synchronize the fuel injection and ignition timing with the engine's cycles. Accurate readings from the sensor ensure that the spark plugs ignite the fuel at the optimal moment, which is crucial for efficient engine operation.

Furthermore, the function of the crankshaft position sensor extends to overall vehicle performance and fuel efficiency. Ensuring that the engine fires accurately helps reduce unnecessary fuel consumption and minimizes exhaust emissions.

Bad crankshaft position sensor symptoms

When a crankshaft position sensor begins to fail, it can cause a variety of symptoms that affect the performance and reliability of your vehicle.

Here are some key indicators that the sensor may be malfunctioning:

Engine Misfires and Rough Idling: If the crankshaft position sensor is not working properly, it can lead to incorrect timing of spark plug firing. This often results in engine misfires, rough idling, or a rough-running engine, as the combustion process becomes irregular.
Difficulty Starting the Vehicle: A failing sensor can cause the engine to struggle when starting. Since the sensor provides critical data needed for the engine to initiate the ignition process, any delays or inaccurate data can make it difficult to start the engine.
Unexpected Stalling: One of the most common symptoms of a bad crankshaft position sensor is the engine unexpectedly stalling while driving. This happens because the sensor fails to send accurate information to the engine's computer, leading to a loss of engine power.
Check Engine Light: The check engine light may illuminate on your dashboard if the ECU detects a problem with the crankshaft position sensor. This is often accompanied by error codes that a mechanic can read with a diagnostic scanner to confirm the crankshaft sensor issue.
Reduced Fuel Efficiency: If the sensor is not providing accurate data, the timing of fuel injection can be off, leading to poorer fuel economy. This inefficiency can significantly increase fuel consumption over time.
Erratic Acceleration: Poor data from the sensor can affect the timing of ignition and fuel injection, leading to unpredictable acceleration. This can make the vehicle feel jerky or hesitant when you press the gas pedal.

Addressing issues with a crankshaft position sensor promptly is crucial to maintain your vehicle's performance and avoid potential damage to the engine.

Tools You Need To Replace a Crankshaft Position Sensor

Below is a list of essential tools that will help you efficiently and safely replace a crankshaft sensor. Ensure you have these items ready before you start the procedure.

Socket Set: Necessary for removing and securing the crankshaft position sensor bolts.
Screwdrivers: Required for disassembling covers and disconnecting wires.
Torque Wrench: Ensures bolts are tightened to the manufacturer's specifications.
Ratchet and Extensions: Helps access bolts in tight spots.
Multimeter: Used to check the sensor’s electrical connections and functionality.
Gloves and Safety Glasses: Protects hands and eyes during the job.

How to Replace a Crankshaft Sensor? DIY Step-by-Step Guide

Step 1: Locate the Sensor

First, consult your vehicle’s service manual to determine the exact location of the crankshaft position sensor. The location can vary significantly between different makes and models, commonly positioned near the bottom of the engine block or sometimes accessible from the top in easier-to-reach areas depending on the vehicle’s design.

After locating the sensor, assess the area for accessibility. In some cases, you might need to remove other components to reach the sensor, so taking a moment to plan your approach can save time during the actual replacement.

Step 2: Disconnect the Battery

Safety should always be your top priority when working on your vehicle. Disconnecting the battery helps prevent any electrical shocks or shorts while you're replacing the sensor. Remove the negative cable first to help ensure safety.

This step also protects the vehicle's electrical system from potential damage while you're working. Once the battery is disconnected, you can proceed without worrying about the electrical current interfering with your work.

Step 3: Access the Sensor

To reach the crankshaft position sensor, you may need to remove components like the air filter housing or other nearby parts. This step can vary greatly depending on your vehicle’s design, so refer back to the service manual for specific guidance on what needs to be removed.

Ensure that you carefully keep track of all screws and bolts. It’s a good practice to use containers or magnetic trays to hold these components, which will simplify reassembly and prevent any small parts from getting lost.

Step 4: Disconnect the Sensor

Carefully unplug the electrical connector from the crankshaft position sensor. It's important to be gentle to avoid damaging the connector, as it is essential for the new sensor's function. Check the connector for any dirt or corrosion and clean it if necessary.

Next, use the appropriate socket to remove the mounting bolt(s) that secure the sensor in place. Keep these bolts safe as you will need them to install the new sensor.

Step 5: Remove the Sensor

Gently pull the sensor out of its mount. If it resists, carefully wiggle it to loosen any buildup or corrosion that may be holding it in place. Avoid using excessive force or tools that could damage the sensor or the surrounding area.

Once removed, inspect the sensor’s seating area for any debris or corrosion that might affect the new sensor's installation. Cleaning the mount can ensure a snug and proper fit for the new sensor.

Step 6: Compare Sensors

Hold the old crankshaft sensor next to the new one to ensure they match in size, shape, and connector type. This is crucial because even a slight difference can lead to malfunction or installation issues.

Also, verify part numbers if available. Using the correct sensor specified by your vehicle manufacturer ensures compatibility and performance.

Step 7: Install the New Sensor

Carefully insert the new crankshaft position sensor into the mounting area. Make sure it fits perfectly without forcing it into place. Once seated properly, reattach the mounting bolt(s) using the socket and tighten them to the manufacturer’s specified torque using your torque wrench.

This precision is important to avoid over-tightening, which can damage the new crankshaft sensor or affect its performance. Proper installation ensures the sensor will function as expected and provide accurate readings to your vehicle's computer system.

Step 8: Reconnect the Electrical Connector

Plug the electrical connector into the new sensor, ensuring it clicks into place. A secure connection is crucial for transmitting the sensor's data accurately to the engine control unit (ECU).

Check the connector again to make sure it is clean and free from any obstructions that could interfere with the signal. This ensures that the new sensor can communicate effectively with the vehicle’s computer.

Step 9: Reassemble and Reconnect Battery

Replace any components you had to remove to access the sensor. Make sure all parts are securely reattached and that all screws and bolts are tightened to their proper specifications. This prevents any loose parts which could lead to further issues down the road.

After reassembly, reconnect the battery, starting with the positive cable, and ensure all connections are tight and secure. This step is vital to restore power to the vehicle and test the new sensor's functionality.

Step 10: Test Your Work

Start the engine to ensure it runs smoothly without any unusual noises or warning lights. Observe the vehicle’s performance; there should be no stalling or rough idling, which can indicate a successful replacement.

Crankshaft Position Sensor Codes

When a crankshaft position sensorbegins to fail or encounters issues, it often triggers specific diagnostic trouble codes (DTCs) in your vehicle’s onboard computer system. These codes help pinpoint the issue with the sensor and guide technicians in troubleshooting and repairing the problem. Here are some common crankshaft position sensor codes:

P0335 - Crankshaft Position Sensor "A" Circuit Malfunction

This code indicates that there is a problem with the electrical circuit involving the crankshaft position sensor. It could be due to faulty wiring, a bad connection, or a defective sensor.

P0336 - Crankshaft Position Sensor "A" Circuit Range/Performance

This code suggests that the sensor's signal is out of range or it's intermittently cutting out. It can indicate erratic sensor operation or issues with sensor alignment and installation.

P0337 - Crankshaft Position Sensor "A" Circuit Low Input

This code is triggered when the sensor’s voltage input is below the expected level, suggesting a short or significant resistance in the circuit.

P0338 - Crankshaft Position Sensor "A" Circuit High Input

Conversely, this code signifies that the sensor's voltage input is higher than normal, which might be due to a wiring short to power.

P0339 - Crankshaft Position Sensor "A" Circuit Intermittent

This code indicates that the sensor's signal is intermittently interrupted. This can be caused by loose connections, damaged wires, or a failing sensor.

Each of these codes requires specific diagnostic steps to confirm the root cause of the problem. Typically, diagnosing a problem with the crankshaft position sensor involves inspecting the sensor itself, checking the wiring and connections, and potentially replacing the crankshaft position sensor if it is found to be defective.

FAQs

1. What is the cost to replace a crankshaft sensor?

The cost to replace a crankshaft sensor can vary widely depending on the make and model of your vehicle but typically ranges from $120 to $300. This price includes both parts and labor, with the sensor itself usually costing between $50 and $100. Factors such as vehicle complexity and the mechanic's labor rate also affect the total cost.

2. How to reset crankshaft position sensor?

To reset a crankshaft position sensor, you typically need to disconnect the car's battery for a few minutes to clear the engine control unit (ECU) memory and reset the crankshaft sensor. After reconnecting the battery, start the vehicle and let it idle for a few minutes to allow the ECU to recalibrate the sensor. This process can vary by vehicle model, so consult your owner's manual for specific instructions.

3. Where crankshaft position sensor is located?

The location of the crankshaft position sensor varies by vehicle make and model but is generally found either near the bottom front of the engine block or next to the transmission bell housing, making crankshaft sensor replacement a variable process. On some cars, it might be accessible from the top, but on others, you may need to lift the vehicle. Always refer to your vehicle's service manual for the exact location in your specific model.

Start Crankshaft Position Sensor Replacement With JB Tools

Starting your DIY crankshaft position sensor replacement is easier when you have top-quality tools from JB Tools. We specialize in providing durable, precise tools that ensure your automotive projects are successful and efficient. Our range includes everything from sockets and screwdrivers to advanced diagnostic scanners, tailored to both professional mechanics and DIY enthusiasts.

At JB Tools, we're not just about selling tools; we're about ensuring your car repair experience is hassle-free. Our robust tools are designed to handle the rigors of automotive repair, and our customer service team is always ready to assist with expert advice. Equip yourself with JB Tools, and tackle your crankshaft position sensor replacement with confidence.