What Are Symptoms of a Bad Crank Shaft Sensor?

Your car depends on a variety of sensors to keep it running smoothly, and the crankshaft position sensor (CPS) is one of the most important. This essential component plays a pivotal role in the engine management system, helping the vehicle regulate ignition timing, fuel injection, and overall performance. By detecting the position and rotational speed of the crankshaft, it generates precise data that is transmitted to the electronic control unit (ECU). If the CPS stops working properly, it can make the engine increasingly unreliable, cause severe problems, or even leave you stranded when your vehicle breaks down.

When a faulty CPS fails to monitor the crankshaft rotation correctly, symptoms like rough idling, sluggish acceleration, and decreased fuel-conscious driving can occur. A bad sensor may disrupt communication between major engine components, resulting in misfires or difficulty starting. If you suspect your CPS is the blame for these issues, expert technicians at Christian Brothers Automotive can help diagnose and resolve the issue. Replacing the part typically costs between $40 and $150, depending on models and replacement needs. Acting quickly can save your vehicle from severe damage and restore smooth, powerful performance.

What’s a Crankshaft Position Sensor?

The crankshaft position sensor (CPS) is a small electronic device that plays a crucial role in keeping your engine running smoothly. Mounted near the crankshaft, it uses a magnet or Hall effect device to detect the position of the crankshaft as it rotates. This sensor sends information to the vehicle’s computer, which uses the data to calculate engine speed and regulate fuel injection, ignition timing, and RPM. Without a functional crankshaft sensor, the engine’s management system struggles to control these processes, potentially leading to poor performance or even severe engine damage.

The crankshaft itself is an incredibly engineered metal component, often about 2 feet long, designed to convert the linear motion of pistons moving up and down into rotational power. This rotational motion is transmitted to countless other parts in the vehicle, powering the entire system. The CPS monitors the position and rotational speed of this vital engine part, ensuring it runs efficiently and safely. In modern cars, the CPS is a critical part of the engine management system, helping to avoid engine damage and maintain optimal performance.

How a Crankshaft Position Sensor Works

The crankshaft position sensor is an important component that keeps your engine running efficiently and safely. Mounted near the crankshaft, it uses a magnet or Hall effect device to detect the position and speed of the crankshaft as it rotates and passes by the sensor. This information is sent to the vehicle’s computer, which uses the data to calculate engine speed and control critical systems like the fuel injection system and ignition timing. Without a properly working sensor, the engine cannot accurately measure its movements, leading to poor performance or even engine damage. To avoid issues, it’s essential to regularly check and replace the sensor to ensure everything is running properly.

Early Warning Signs of a Failing Crankshaft Position Sensor

Dashboard Warning: Check Engine Light

When the crankshaft position sensor begins to fail, one of the first symptoms is the Check Engine Light illuminating on your dashboard. This happens when the sensor sends incorrect signals or no signal to the engine control module (ECU). Without accurate readings, your engine may struggle with ignition timing, starting, or even intermittent stalling while driving or idling. You might also notice misfires, rough idling, and vibrations, which make the car feel unstable.

Decline in Fuel Efficiency and Performance

Another sign of a faulty sensor is a noticeable decline in fuel efficiency. The sensor’s failure can throw off the timing, leading to inefficient combustion and increased fuel consumption. A lack of smooth acceleration is also common, where the car hesitates to pick up speed. If neglected, these issues can cause sporadic power production and stronger exhaust smells, as unburned or partially burned fuel accumulates in the exhaust system, potentially damaging the catalytic converter.

Preventative Measures to Avoid Costly Repairs

To avoid major issues, recognize these symptoms early and have the sensor inspected by a qualified mechanic. Schedule replacement around the 100,000-mile mark to minimize the risk of being stranded due to a completely failed sensor. Addressing the problem early ensures the engine control module receives accurate data, maintaining optimal vehicle performance and preventing damage to critical engine parts.

How to Tell if Your Crankshaft is Faulty

If your engine refuses to start despite the ignition clicking, you can often blame a faulty crankshaft position sensor. The sensor’s failure causes trouble knowing when to fire spark plugs or inject fuel, leaving you with little luck getting the engine started

How to Test a Crankshaft Position Sensor?

Locate the Crankshaft Position Sensor

The first step in testing the crankshaft position sensor is to locate it under the hood. It is commonly found near the front or back of the bell housing, often tucked behind other components. Begin by inspecting the sensor and its housing for any visible damage, dirt, oil, or debris that might block its function. These contaminants can stop the sensor from working, so cleaning and re-installing it could fix the issue without further steps.

Check for Trouble Codes

Use an OBD-II scanner to perform a scan test for any diagnostic trouble codes (DTCs) stored in the vehicle’s computer. These codes can help identify issues like misfires, timing problems, or fuel injection errors related to the crankshaft position sensor. If DTCs plausibly indicate the sensor as the likely culprit, you may need to proceed with physical and electrical testing.

Test the Sensor with a Multimeter

With a multimeter in hand, set it to the ohms setting for resistance measurement. The resistance of a working crankshaft position sensor should generally fall between 200 and 1,000 ohms, depending on the vehicle model. Have a helper crank the engine while you monitor the meter, which should rapidly switch between zero and five volts. If the results fall outside this range or show no activity, the sensor might be bad and should be replaced.

Inspect Wiring and Connections

Inspect the wiring connections for breaks, loose connectors, or corrosion, as these can prevent accurate signals from reaching the engine control module. If the connector is loose or corroded, a quick fix like tightening or cleaning might resolve the issue. When diagnosing, compare the sensor’s output signal to a known good CPS using diagnostic equipment. For difficult cases, a trusted mechanic with specialized tools and knowledge can help confirm the diagnosis.

What Causes Damage to Your Crankshaft Sensor?

Heat and Environmental Stress

Over time, general wear and tear on your car can take a toll on the crankshaft position sensor. Extreme heat from the engine or hot weather can damage the sensor’s housing, which is often made of plastic. When the engine becomes overheated, it may cause parts to melt or degrade, leading to a malfunction. Additionally, the sensor can be exposed to dirt, water, or other contaminants, which might interfere with its performance or cause long-term damage.

Electrical and Wiring Issues

One common cause of failure is worn-out or damaged wiring. If the sensor wiring becomes rubbed through, cracked, or corroded, it can disrupt the signals sent to the engine control module. This interruption can lead to a variety of electrical problems, including inaccurate readings or complete sensor malfunction. Even minor issues, such as a loose connector, can result in the crankshaft sensor not working properly, making it essential to check the wiring harness for corrosion or damage.

Mechanical Damage and Impact

Physical impacts can also lead to crankshaft position sensor damage. For example, if the sensor is hit during maintenance or comes into contact with a moving part, it may result in inconsistent readings or total failure. The reluctor wheel, which works with the sensor to monitor engine performance, can also become wobbly or dirty, further causing inaccurate readings. These mechanical issues require careful inspection to ensure all components are aligned and free from debris.

Consequences of Ignoring Sensor Problems

Ignoring a bad crankshaft position sensor can lead to serious consequences for your vehicle. Since the sensor plays a crucial role in managing ignition timing and fuel injection, any disruption can cause inefficient combustion, increased stress on engine parts, and poor performance. This might result in rough idling, prolonged cranking, or even sudden stalling, which can be dangerous, especially at high speeds or in traffic. Addressing the issue early can save you from engine damage, decreased fuel efficiency, and costly repairs.

Need Help with Your Engine & Crankshaft Problems? Request Your Repair Today!

If you’re noticing symptoms like engine misfiring, rough idling, or difficulty starting, it may be time to get your crankshaft sensor checked by a professional mechanic. The issue could be more complicated than a quick fix, and it’s essential to have it diagnosed correctly to avoid further damage. Christian Brothers Automotive offers a free courtesy inspection to locate and address any problems with your vehicle. Our expert technicians are ready to help with repair recommendations and services that ensure long-lasting results.

Whether you’re dealing with intermittent issues or are unsure about diagnosing and replacing the sensor, our team at Christian Brothers Automotive is capable of handling major repairs. We offer high-quality replacement parts, and our warranty covers the service for 3 years or 36,000 miles. Schedule a visit today to get your vehicle back to its optimal health, and let us take the stress out of the repair process.

FAQs

What kills crankshaft sensor?

A crank sensor can fail due to a short in the wiring, either to ground or voltage, damaging its innards and often affecting the driver in the corresponding module. This can prevent the sensor from working properly.

Do you have to relearn after replacing the crankshaft position sensor?

After replacing a crankshaft sensor, you may need to relearn the sensor in some vehicles. This helps ensure that the onboard computer can properly identify the new sensor and clear any stored trouble codes like DTCs related to misfires, timing, or injection.

Would a crank sensor throw a code?

Yes, a faulty crank sensor will often trigger a Check Engine Light and store trouble codes in the onboard computer. These DTCs can be directly related to issues such as misfires, timing, or injection problems.

What to do after replacing a crankshaft sensor?

After installing a new crankshaft sensor, there’s no need for programming or recalibration. These plug-and-play crankshaft sensors should start to function properly once installed, without the need for any additional programming in most vehicles.

How do you temporarily fix a crankshaft sensor?

If your Check Engine Light is on, first check the error code to confirm if the crankshaft position sensor is the problem. If the engine is overheated, pull over to a safe area, stop, turn off the engine, and let it rest and cool down before starting again.

How to start a car with a bad crankshaft sensor?

Starting a vehicle with a bad crankshaft sensor can be risky and is unlikely to work. If needed, disconnect the damaged sensor, spray some starter fluid into the throttle body, and try cranking the engine to start the vehicle.