Your vehicle’s crankshaft position sensor (CKP sensor) is a vital part of its engine control system. If the CKP sensor isn’t functioning properly, your car engine won’t run properly and could suffer severe damage due to incorrect fuel delivery and timing.
In this article, we’ll go over the most common symptoms of a bad crankshaft position sensor and examine the main reasons why they fail.
What are the Signs of a Bad Crankshaft Position Sensor?
Correctly identifying the symptoms of a bad crankshaft position sensor can help prevent further damage and costlier repairs. Look out for the following tell-tale signs:
Difficulty Starting Your Vehicle
If your vehicle has difficulty starting or doesn’t start at all, it could be because of a bad crankshaft position sensor. If the CKP sensor isn’t sending the correct signals, the engine control unit (ECU) may struggle to determine the precise timing for fuel injection and ignition, making it difficult to start your vehicle.
Check Engine Light is On
If the ECU determines that the CKP sensor’s readings aren’t within normal values, it will activate the Check Engine Light and register a corresponding trouble code.
Engine Stall
Sudden stalling while driving or at idle is a significant warning sign that your CKP sensor may be failing. Without accurate data from the sensor, the engine may lose power unexpectedly.
Engine Misfire
If you hear (or feel) a brief stutter in the car engine, it may be a sign of misfiring cylinders due to a malfunctioning crankshaft position sensor. A failing CKP sensor cannot provide accurate information about piston positioning in the engine, causing the cylinders to misfire.
Acceleration Issues
With inaccurate input coming from the CKP sensor, the ECU cannot make adjustments to the spark timing and fuel injections as engine speed increases. This results in sluggish or uneven acceleration.
Fuel Efficiency Issues
Inaccurate timing information from the CKP sensor means the fuel injectors won’t be able to pump gas into the engine efficiently. The engine will end up consuming more gas than it needs, reducing overall fuel efficiency.
Engine Vibration
Once the CKP sensor starts to fail, you’ll notice a major increase in engine vibration. This is due to the ECU receiving incorrect data, which can affect engine operation.
What Causes a Crankshaft Position Sensor to Go Bad?
The following factors could cause a crankshaft position sensor to fail:
Exposure to Heat and Vibrations
The CKP sensor is often located near the engine or exhaust system. This exposes it to high temperatures and strong vibrations. Over time, this constant exposure will cause the sensor’s internal components to fail.
Exposure to Contaminants
Oil and coolant leaks could contaminate the CKP sensor, leading to improper readings or complete sensor failure.
Electrical Issues
Damaged or corroded wiring, poor grounding, or loose connectors can interrupt the signal, causing the sensor to malfunction.
Physical Damage
Direct impact from road debris and improper handling during engine repairs could seriously damage the sensor.
Gradual Wear and Tear
Continuous use can cause the CKP sensor to wear out over time. Internal components, such as the magnets or circuitry, can degrade with age.
Manufacturing Defects
Occasionally, the sensor might fail prematurely due to manufacturing defects or the use of substandard materials.
What Does a Crankshaft Position Sensor Do?
Found in both diesel and petrol engines, the crankshaft position sensor or CKP sensor monitors the crankshaft’s position and rotational speed. This data is relayed to the ECU, enabling precise control of fuel injection and ignition timing. This optimization is key to ensuring optimal engine performance.
By accurately tracking the crankshaft’s position, the CKP sensor indirectly informs the ECU about the position of the pistons inside the engine. This allows for perfect timing of the spark plugs, maximizing combustion efficiency. The end result is an engine that runs smoothly, efficiently, and with reduced emissions.
Where is the Crankshaft Position Sensor Located?
The location of the crankshaft position sensor will depend on your vehicle’s make, model, and engine design. It’s typically located in the timing cover (at the front of the engine block) or near the engine’s crankshaft (since it needs to monitor the crankshaft’s position and rotational speed). Other possible locations include near the transmission bell housing or underneath the engine.
Crankshaft Position Sensor Replacement Cost
The overall cost of replacing a faulty crankshaft position sensor is between $650 to $800.
The estimated cost of the replacement parts is between $50 to $100, depending on the manufacturer. Meanwhile, the estimated cost of labor is between $600 to $700 (or more). Additional parts that may need to be replaced (e.g. gaskets) may add another $50 to $100 to your bill.
The location of the crankshaft position sensor and overall complexity of the job will also impact the overall cost. CKP sensors that are mounted inside the timing cover or transmission bell housing are very difficult to access. The obstructing parts will have to be removed in order to access the CKP sensor, causing the cost of labor and parts to go up.
The final price excludes taxes and fees, the cost of labor and goods in your area, and related repairs. Also, keep in mind that these prices are simply estimates. It’s best to get quotes from multiple repair shops in your area to get a better idea of how much replacing your crankshaft position sensor will cost.
Frequently Asked Questions
What scanner can relearn a crankshaft position sensor?
To relearn a crankshaft position sensor, you’ll typically need a diagnostic scanner that can perform advanced functions, including reprogramming and relearning. Some scanners that can perform these functions include professional diagnostic scanners (e.g. Autel, Bosch); OEM scan tools (like those offered by BMW for its vehicles); and advanced automotive diagnostic tools (e.g. Foxwell NT624).
However, if you’re looking for cost savings and have chosen a reputable aftermarket brand, then an aftermarket sensor might be a viable option. Make sure to research the brand thoroughly to avoid any compatibility or fitment issues.
Can you clean a crankshaft position sensor?
Yes, you can clean a crankshaft position sensor. You’ll need wrenches and sockets (to remove the sensor), a clean cloth, and a sensor-safe cleaning solvent (e.g. a brake cleaner or electric parts cleaner). After locating the sensor, disconnect the battery and remove it from its mounting location using your socket or wrench.
Spray the sensor with the cleaning solvent and wipe away the debris. Once it’s clean and completely dry, reinstall it. Finally, reconnect the battery and start the engine to see if the issue has been resolved.
What happens if you don’t relearn a crankshaft position sensor?
Failure to perform a relearn procedure after replacing the crankshaft position sensor could lead to a variety of engine performance issues. Potential issues include triggering the Check Engine Light, engine misfires, stalling or hard starting, and inconsistent power delivery. Relearning helps the ECU properly calibrate the new sensor, ensuring accurate engine timing and performance.
Can I replace a BMW crankshaft position sensor with Duralast?
Yes, you can replace a BMW crankshaft position sensor with a Duralast CKP sensor as long as the part is compatible with your specific BMW model. Before making your purchase, make sure the Duralast sensor meets the specifications required for your BMW model to avoid any compatibility issues. It’s also a good idea to check the warranty and return policies on the Duralast sensor in case it does not meet your expectations.
Does a BMW crankshaft position sensor have to be OEM?
While it’s best to purchase OEM when replacing a BMW crankshaft position sensor, this isn’t a hard and fast rule. If you prioritize reliability and compatibility, and want to maintain existing warranties in your vehicle, then buy an OEM sensor.
