Crankshaft Position Sensor Failure Fixes

Overview

This article explains how the crankshaft position sensor works as a critical component for engine timing, with key symptoms of failure including engine misfires, hard starting, stalling, check engine light illumination, and poor fuel economy. It provides a complete guide to diagnosing sensor issues, step-by-step replacement instructions, preventative maintenance tips, and cost considerations for both DIY repairs and professional service.

Table of Contents

• What Is a Crankshaft Position Sensor?
• Symptoms of Crankshaft Position Sensor Failure
• Common Causes of Sensor Failure
• Diagnosing Crankshaft Position Sensor Issues
• How to Replace a Crankshaft Position Sensor
• Preventative Maintenance Tips
• Costs and Considerations
• Conclusion
• Frequently Asked Questions

What Is a Crankshaft Position Sensor?

You know that feeling when your car suddenly sputters and leaves you stranded on the side of the road? Often the culprit is no larger than a matchbox—the crankshaft position sensor. This tiny electronic component plays an outsized role in your vehicle’s performance, acting like the conductor of your engine’s orchestra.

In my 20 years of turning wrenches, I’ve seen countless drivers scratching their heads over mysterious engine problems that all pointed back to this humble sensor. But what exactly does it do? Picture your engine as a complex timepiece, with dozens of components that must move in perfect synchronization. The crankshaft position sensor monitors the position and rotational speed of your crankshaft, feeding this vital information to your engine’s computer (ECU).

Without this critical data, your engine wouldn’t know when to inject fuel or fire the spark plugs. It’s like trying to conduct a symphony blindfolded—impossible to coordinate properly. The sensor typically consists of a magnetic pickup or Hall effect sensor that reads the position of teeth or reluctors on a ring attached to the crankshaft.

This precision timing is what allows your engine to achieve that smooth, continuous power delivery you expect when you press the accelerator. When the crankshaft position sensor begins to fail, that harmony quickly deteriorates into chaos.

Symptoms of Crankshaft Position Sensor Failure

When your crankshaft position sensor starts waving the white flag, your vehicle will speak to you through a language of performance issues. Learning to interpret these signals can save you from being stranded at the worst possible moment.

Engine Misfires and Rough Running

Have you ever felt your car shudder or hesitate while driving, almost like it’s having a brief coughing fit? I remember driving my own truck when it suddenly began bucking like a bronco at a rodeo. The engine was misfiring because the failing sensor was sending erratic timing signals, causing cylinders to fire at the wrong moment.

This rough running often feels most noticeable at consistent speeds or during acceleration. Your engine might suddenly lose power or jerk unexpectedly, creating a driving experience that’s about as smooth as a rollercoaster on a dirt road.

Hard Starting or No-Start Conditions

Perhaps the most frustrating symptom is when you turn the key and… nothing happens. Well, not nothing—the engine cranks, but it won’t catch and run. Without accurate crankshaft position information, your engine’s computer can’t properly time the ignition and fuel injection systems.

This no-start condition might come and go, often teasing you with intermittent operation before failing completely. I’ve seen many cases where vehicles start fine in the morning but refuse to restart after stopping for lunch or errands—a classic sign of a sensor that’s failing when it warms up.

Check Engine Light Illumination

That amber warning light on your dashboard isn’t just there for decoration. When your engine’s computer detects irregular signals from the crankshaft position sensor, it will trigger the check engine light and store a specific diagnostic trouble code.

Common codes related to crankshaft position sensor failures include P0335 (Crankshaft Position Sensor Circuit Malfunction), P0336 (Crankshaft Position Sensor Performance), and similar codes that vary by manufacturer. Don’t ignore this warning—it’s your car’s way of asking for help before the problem worsens.

Stalling or Unexpected Shutdown

Picture this: you’re cruising along when suddenly your engine dies completely. This heart-stopping moment—which I’ve experienced myself on a busy highway—often results from a crankshaft position sensor that’s failed while driving.

Since the sensor provides the timing reference for the ignition system, a complete failure means your engine simply can’t run. Your vehicle might restart after cooling down, only to fail again later, creating a dangerous and unpredictable driving situation.

Poor Fuel Economy

Have you noticed more frequent trips to the gas station lately? A faulty crankshaft position sensor can cause your fuel efficiency to plummet faster than a stone in water. When timing is off, your engine may use more fuel than necessary, sometimes as much as 10-20% more.

This symptom often flies under the radar because it develops gradually, but your wallet certainly feels the difference. One customer came to me complaining about poor gas mileage, only to discover his fuel economy improved by nearly 5 MPG after replacing a failing sensor.

Common Causes of Sensor Failure

Understanding why these sensors fail can help you prevent future problems and extend the life of your replacement sensor. Let’s look at the usual suspects:

Heat Damage

Positioned close to the engine block, crankshaft position sensors endure extreme temperature cycles. Modern engines routinely reach temperatures exceeding 200°F, and this heat is the sensor’s worst enemy. Over time, this thermal stress can degrade the internal components, causing erratic performance or complete failure.

I’ve seen sensors that literally melted from excessive heat, especially in vehicles with cooling system issues or those operated in extreme conditions. The sensor’s plastic housing and internal electronics simply aren’t designed to withstand prolonged exposure to temperatures beyond their design specifications.

Vibration Fatigue

Your engine is essentially a controlled explosion machine, creating significant vibration that transfers to all attached components. These constant vibrations can loosen connections, damage internal sensor components, and create microfractures in circuit boards or soldered connections.

Vehicles driven frequently on rough roads or those with engine mount issues experience accelerated sensor wear from excessive vibration. It’s like shaking a delicate electronic device repeatedly—eventually, something will break.

Oil and Debris Contamination

Many crankshaft position sensors are mounted in locations vulnerable to oil leaks or debris accumulation. When engine oil seeps into the sensor connector or housing, it can degrade the electrical connections and cause short circuits or signal degradation.

I once worked on a vehicle where the sensor was completely saturated with oil from a leaking front main seal. The oil had crept into the sensor’s internal components, causing intermittent failures that were maddening to diagnose until we identified the true source of the problem.

Wiring Issues

The electrical connection between the sensor and the engine control module is vulnerable to damage. Wiring harnesses can chafe against engine components, connections can corrode, and vibration can loosen plugs. These issues often mimic the symptoms of a failed sensor but require a different repair approach.

As automotive experts note, nearly 30% of sensor-related issues are actually problems with wiring or connections rather than the sensor itself. Always inspect the entire circuit before simply replacing parts.

Manufacturing Defects

Not all sensors are created equal. Some vehicles are notorious for problematic sensors from the factory, which may fail prematurely regardless of driving conditions. Aftermarket replacement parts can vary widely in quality, with budget options often failing much sooner than OEM or premium alternatives.

I’ve seen certain vehicle models come through my shop repeatedly with the same sensor issues, indicating design flaws in the original components. In these cases, upgrading to an improved design can prevent recurring failures.

Diagnosing Crankshaft Position Sensor Issues

Before you start replacing parts, it’s crucial to confirm that the crankshaft position sensor is actually the culprit. Let me walk you through the diagnostic process I use in my shop:

Scan for Diagnostic Trouble Codes

The most efficient first step is to connect an OBD-II scanner to retrieve any stored diagnostic trouble codes. These digital clues can point you directly to the problem or at least narrow down the possibilities.

Common crankshaft position sensor codes include:

• P0335: Crankshaft Position Sensor Circuit Malfunction
• P0336: Crankshaft Position Sensor Range/Performance
• P0337: Crankshaft Position Sensor Circuit Low Input
• P0338: Crankshaft Position Sensor Circuit High Input
• P0339: Crankshaft Position Sensor Circuit Intermittent

Remember, though, that codes only tell part of the story. I’ve seen many instances where other problems triggered sensor-related codes, which is why thorough diagnosis is essential. You can get a professional car diagnostic service or purchase an affordable scanner for home use.

Visual Inspection

Sometimes the simplest approach yields the most information. Visually inspect the sensor and its wiring harness for obvious damage or contamination. Look for:

• Oil or coolant contamination
• Damaged, burnt, or melted wiring
• Loose or corroded electrical connections
• Physical damage to the sensor housing
• Debris accumulation around the sensor

Last month, I saved a customer several hundred dollars by simply cleaning a connector that was corroded rather than replacing the sensor itself. Don’t skip this basic but valuable diagnostic step!

Testing Sensor Output

For a more definitive diagnosis, you can test the sensor’s electrical output. This typically requires a digital multimeter or oscilloscope, depending on the sensor type:

For magnetic (variable reluctance) sensors, measure the resistance between the sensor terminals using a multimeter. Compare your readings to the manufacturer’s specifications, typically found in the service manual. Most sensors should read between 500-1500 ohms, but this varies by vehicle.

For Hall effect sensors, you’ll need to check for proper voltage reference and return signals. These sensors typically require 5-12 volts reference voltage from the ECU and return a digital on/off signal as the crankshaft rotates. An oscilloscope provides the most accurate way to visualize this signal pattern.

If these tests sound intimidating, don’t worry—they’re second nature to professional mechanics with the right equipment. Sometimes the most economical approach is to have a check engine light issue diagnosed professionally before attempting repairs yourself.

How to Replace a Crankshaft Position Sensor

If you’ve confirmed that your crankshaft position sensor is the problem, replacing it can often be a straightforward DIY job. Let me guide you through the process I’ve performed hundreds of times in my career:

Tools and Materials Needed

Before you start, gather these essential tools:

• Socket set and ratchet (metric or standard, depending on your vehicle)
• Torque wrench
• Flathead and Phillips screwdrivers
• New crankshaft position sensor (OEM recommended)
• Anti-seize compound
• Shop towels
• Safety glasses
• Work gloves
• Vehicle service manual or online repair guide

Having everything ready before you start will prevent that frustrating mid-job parts store run that seems to happen on every DIY project. Trust me, I learned this lesson the hard way many times before making it a habit to prep thoroughly.

Locating the Sensor

Crankshaft position sensors are located in different places depending on your vehicle make and model. Common locations include:

• On the front of the engine block near the crankshaft pulley
• On the side of the engine block, often near the starter motor
• At the rear of the engine near the transmission bell housing
• Behind the timing cover (requires more extensive disassembly)

Your vehicle’s service manual will provide the exact location. I once spent an hour looking for a sensor on a Ford that was hidden behind the starter motor—a detail that would have been immediately apparent had I checked the manual first! Learn from my mistakes and consult your service information before diving in.

Step-by-Step Replacement Process

Now let’s get to the actual replacement:

1. Safety first: Disconnect the negative battery terminal to prevent electrical shorts or accidental engine starting during your work. I once skipped this step and bumped the ignition—let’s just say it made for an exciting afternoon.

2. Access the sensor: In some vehicles, you may need to remove certain components to reach the sensor. This could include air intake ducts, splash shields, or in rare cases, even the starter motor. Follow your service manual’s guidance.

3. Disconnect the electrical connector: Press the tab or release mechanism on the sensor’s electrical connector and carefully pull it free. Never yank on the wires themselves—always grip the connector body.

4. Remove the mounting bolt(s): Most sensors are held in place by one or two bolts. Remove these carefully, keeping track of their orientation for reinstallation. A magnetic socket or tray can prevent dropping bolts into the abyss of your engine bay.

5. Extract the sensor: Gently remove the sensor from its mounting hole. It may require slight wiggling if it’s been in place for a long time. If it’s stuck, check for additional mounting hardware rather than forcing it.

6. Compare the new sensor: Before installation, compare your new sensor with the old one to ensure they match in size, connector type, and mounting configuration.

7. Install the new sensor: Apply a small amount of anti-seize compound to the sensor body (not the electrical connections!) if recommended by your service manual. This will make future removal easier. Insert the new sensor into the mounting hole.

8. Secure the mounting bolt(s): Reinstall and tighten the mounting bolts to the torque specification in your service manual. As Motor Magazine highlights, proper torque is crucial—too loose and the sensor may shift position, too tight and you risk damaging the new sensor.

9. Reconnect the electrical connector: Push the electrical connector onto the new sensor until you hear it click, confirming proper engagement.

10. Reconnect the battery: Reattach the negative battery terminal and tighten securely.

11. Test operation: Start the vehicle to confirm proper operation. The engine should start promptly and run smoothly. Take a short test drive to ensure all symptoms have been resolved.

Preventative Maintenance Tips

An ounce of prevention is worth a pound of cure, especially when it comes to sensor failures. Here are some strategies I recommend to my customers for extending sensor life:

Address Oil Leaks Promptly

Oil contamination is a leading cause of premature sensor failure. If you notice oil seeping from gaskets or seals near your crankshaft position sensor, don’t procrastinate on those repairs. What might seem like a minor leak today could be destroying your new sensor tomorrow.

I’ve lost count of how many times I’ve seen customers replace the same sensor repeatedly because they ignored the oil leak that caused the failure in the first place. Fix the root cause, not just the symptom.

Maintain Clean Electrical Connections

Electrical connections are the Achilles’ heel of modern vehicles. During routine maintenance, inspect the sensor connector for corrosion, dirt, or damage. A quick spray of electrical contact cleaner can prevent intermittent connection issues that mimic sensor failures.

For vehicles operated in coastal areas or regions where road salt is used, consider applying dielectric grease to sensor connections during installation. This simple step has saved many of my customers from the headaches of corrosion-related failures.

Consider Preemptive Replacement

For vehicles known to have problematic crankshaft position sensors, consider replacing the sensor preemptively during major service intervals once your vehicle exceeds 80,000 miles. This is especially true for certain makes and models with documented sensor issues.

The cost of a planned replacement during routine service is far less than an emergency repair after being stranded on the roadside. It’s a bit like changing your smoke detector batteries—a small, planned inconvenience prevents a major emergency.

Use Quality Parts

The temptation to save a few dollars with bargain-bin sensors is strong, but I’ve seen enough repeat failures to advise against it. OEM or high-quality aftermarket sensors from reputable manufacturers typically last significantly longer.

In my experience, the price difference between budget and quality sensors is usually recovered many times over in extended service life and reliability. I’ve had customers return with failed aftermarket sensors within months, while quality replacements often last years.

Costs and Considerations

Let’s talk about what you can expect to spend when dealing with crankshaft position sensor issues:

Part Costs

Crankshaft position sensor prices vary widely depending on your vehicle:

• OEM sensors typically range from $75-$200
• Quality aftermarket sensors usually cost $40-$120
• Budget aftermarket options can be found for $20-$50 (though I rarely recommend these)

Luxury and performance vehicles often have more expensive sensors, while common domestic and Asian models tend to be more affordable. I’ve replaced sensors on Mercedes-Benz vehicles that cost nearly three times what the same job would require on a Toyota.

Labor Costs

Professional installation typically runs between $75-$200 for labor, depending on your vehicle and location. The wide range exists because sensor accessibility varies dramatically between models.

Some vehicles allow direct access to the sensor with minimal disassembly, resulting in a quick 30-minute job. Others require removing multiple components to gain access, potentially extending the job to 2+ hours. Always get a specific quote for your vehicle rather than relying on general estimates.

DIY Savings

Replacing the sensor yourself can save $75-$200 in labor costs. For many vehicles, this is a relatively straightforward job requiring basic hand tools and mechanical aptitude. However, some vehicles present significant challenges that might make professional installation more practical.

Before attempting DIY replacement, research your specific vehicle model to understand the complexity involved. What takes a professional 30 minutes might take a novice several hours, especially if special tools or extensive disassembly is required.

Cost vs. Benefit Analysis

When facing crankshaft position sensor issues, consider these factors in your decision-making process:

• Vehicle age and value: More extensive repairs might not be economically sensible for older, lower-value vehicles
• Driving needs: Daily commuters need more immediate and reliable solutions than occasional-use vehicles
• Mechanical ability: Your comfort level with DIY repairs affects the true cost calculation
• Peripheral issues: Related problems like oil leaks should be addressed simultaneously for best results

I always advise my customers to consider the complete picture rather than focusing solely on the immediate repair cost. Sometimes spending a bit more upfront prevents costly headaches down the road.

Conclusion

The crankshaft position sensor may be small, but its impact on your vehicle’s performance is anything but. Through my years turning wrenches, I’ve seen how this tiny component can bring even the most powerful engines to a complete standstill when it fails.

Remember, the key symptoms of crankshaft position sensor failure include rough running, starting problems, check engine light illumination, unexpected stalling, and reduced fuel economy. Catching these warning signs early can prevent you from being stranded at the worst possible moment.

Whether you choose to tackle the replacement yourself or trust a professional, understanding the diagnosis and repair process empowers you to make informed decisions about your vehicle’s care. And don’t forget those preventative measures—addressing oil leaks, maintaining clean electrical connections, and using quality parts can significantly extend your sensor’s life.

Your vehicle relies on the harmonious operation of all its components, from the largest to the smallest. By giving proper attention to often-overlooked parts like the crankshaft position sensor, you’ll enjoy more reliable transportation and fewer unexpected repair bills.

Have you dealt with crankshaft position sensor issues? I’d love to hear about your experience in the comments section below!

Frequently Asked Questions

How long does a crankshaft position sensor typically last?

Most crankshaft position sensors last between 30,000 and 120,000 miles, depending on vehicle make, driving conditions, and sensor quality. OEM sensors generally outlast aftermarket alternatives.

Can I drive with a failing crankshaft position sensor?

Driving with a failing sensor is not recommended as it could leave you stranded or cause the engine to stall unexpectedly in traffic. These unpredictable failures create dangerous driving situations.

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

Total replacement cost typically ranges from $75-$400 depending on your vehicle, parts quality, and labor rates. DIY replacement eliminates labor costs, saving $75-$200 on average.

Will a bad crankshaft position sensor throw a check engine light?

Yes, a failing crankshaft position sensor will usually trigger the check engine light and store specific diagnostic trouble codes. Common codes include P0335, P0336, P0337, and P0338.

How do I know if I need a new crankshaft position sensor?

Key symptoms include engine misfires, hard starting, stalling, poor acceleration, and reduced fuel economy. Definitive diagnosis requires scanning for trouble codes and testing sensor output with appropriate tools.