Although the crankshaft position sensor is a somewhat complex piece of machinery and you might be apprehensive about repairing it yourself, you shouldn’t be. You can replace your own crankshaft sensor with the correct equipment, some work, and clear instructions.
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What signs would point to a crankshaft position sensor failure?
Signs of a Malfunctioning Crankshaft Position Sensor
- Check engine light is on.
- Engine won’t turn on.
- Stalling or hard starting
- Engine misfires and runs rough.
- decreased fuel efficiency
What location is the crankshaft sensor?
A car is said to require both fuel and a spark to start and run. That is correct, but it also requires air, compression, and roughly accurate time. Despite the little quibbles, it’s still a very practical proverb for vintage cars, which for me are anything from 1974 and older. The “fuel and spark clich,” however, becomes less applicable the newer an automobile gets. Because of the car’s growing complexity, there are more things that can prevent gasoline and spark from occurring, even if their existence is still necessary.
Federal emissions regulations received a significant modification in 1975. Unleaded fuel, catalytic converters, oxygen sensors, and lean-running engines met the new, stricter criteria, yet many cars had poor performance. Early in the 1980s, several manufacturers realized that electronic fuel injection (EFI) was the optimum method for balancing emissions, power, and fuel efficiency. The majority of automobiles had jumped on the EFI train before the decade’s end.
The electronic control unit (ECU) of the car uses a crankshaft position sensor, also known as a crank angle sensor (abbreviated as either CPS or CKP), to tell it where the engine is in its rotation cycle so it knows when to fire the fuel injectors and time the spark. All but the most basic EFI systems have used this sensor since the beginning.
The so-called OBD-II diagnostic system, which enables a standard code reader to be placed into a standard plug and read fault codes in the vehicle’s emissions monitoring system, was made mandatory for all cars sold in the United States starting in 1996. While many insignificant emissions problems, evaporative leaks, and similar issues will set off a code and illuminate the dreaded check engine light without affecting drivability at all, a damaged crankshaft position sensor is one of the most common issues to suddenly result in a no-start condition in a modern vehicle. This issue will also set off a code. Therefore, if your vehicle was manufactured in 1996 or after, the most frequent way to diagnose a faulty crank sensor is to connect a code reader, read the error code, and then check to see if the crank sensor is identified as the problem. However, you’ll have to diagnose it yourself if your vehicle is pre-OBD-II.
It depends on the model how the crank sensor branches off the troubleshooting tree. On the majority of vehicles, it will have an impact on both spark and injector firing, but on some, the fuel pump cannot operate at all without the ECU receiving the crank signal.
Crankshaft position sensors come in two basic varieties, just like other rotating sensors like ABS or wheel speed. Variable Reluctance Transducers are passive sensors used by the majority of pre-1996 automobiles (VRT). A stationary magnet is encased in a coil of wire, and a reluctor wheel, a rotating toothed mechanism, passes by it as it rotates. The flywheel itself serves as the reluctor wheel for a crank sensor, which frequently reads the flywheel’s teeth or other reference markings. The magnetic field is impacted as the teeth move close to the magnet. The movement of the teeth through the sensor generates an up-and-down signal that closely resembles a sine wave because a changing magnetic field generates an electric field. The signal’s peaks not only increase stronger as the flywheel spins faster, but they also get closer together. One or more teeth on the reluctor are typically missing when a VRT is used as a crank sensor, leaving a gap in the signal that the vehicle’s ECU detects at Top Dead Center (TDC) for cylinder #1.
Some vehicles have two distinct crank sensorsone that detects only TDC and the other that gauges actual rotation. The first in this scenario is typically referred to as the crankshaft reference sensor, and the second could be referred to as the crank angle or crank speed sensor.
The Hall Effect sensor is the alternative kind of sensor. These come in a variety of forms, but contemporary examples often have a ring of magnets pressed into the rotating part. The Hall Effect device’s semiconductor detects the passing magnets, and integrated electronics tidy up the signal before it is produced as a square wave. VRTs were generally superseded with Hall Effect devices between the mid-1990s and the early 2000s. They are typically less prone to interference and smaller than VRTs.
Physical inspection is the initial step in crank sensor troubleshooting. The sensor is typically found on the transmission bellhousing or behind the crankshaft pulley since it can be found either at the front or back of the crankshaft. The sensor and reluctor should have a very small air gap, typically of a millimeter or two. Therefore, if the sensor has become loose, the mounting bracket has cracked, the bolt holding it has backed out, or another issue, this can reduce the signal intensity and result in failure.
Next, closely examine the wiring. The cable into the back of the sensor can suffer damage from heat and oil leaks. After that, follow the cable back to the wiring harness connector where it connects to another connector after leaving the sensor. Although there is frequently a pigtail, the connector can occasionally be found built right into the sensor’s body. The connector may be loose or fractured, the mating pins may have pushed out the rear, corrosion may have crept in, or the connector may be removed. Re-mating the connector will sometimes solve the issue.
Testing comes next if inspection doesn’t identify and fix a problem. Depending on the type you have, you can test the crank sensor directly with varying degrees of simplicity. You can directly test it if it’s the more traditional passive VRT-style sensor found in the majority of pre-OBD-II vehicles, but if it’s the more modern three-wire Hall Effect sensor, most people just rely on connecting a code reader or scan tool to the OBD-II socket and checking for a crankshaft sensor-related fault.
First, let’s examine the VRT sensor. There are frequently simply two wiressignal and groundbecause these sensors are passive, not powered. To protect the signal from interference, some VRT sensors, however, have a braided sheath inside the cable. This sheath may have a third wire on the connector. If you’re unsure of the type of sensor you have, you can identify it by setting a multimeter to measure DC voltage, unplugging the sensor from the connector, connecting the black probe to chassis ground, turning the key to the ignition, and touching the red probe to each pin on the connector’s wiring harness side. One of them is a Hall Effect sensor if it registers somewhere around five or twelve volts. It’s a VRT if none of them do.
You may have been instructed that using a multimeter to measure the resistance between the sensor’s ground and signal pins is the best approach to test a VRT-based crank sensor. Since the sensor is just a coil of wire wrapped around a magnet, its resistance should be minimalat most one ohm. The sensor needs to be changed if the resistance is infinite, which indicates that there is a damaged wire in the cable or coil. You can perform this, but it won’t provide a conclusive test as all it tells you is that the wire isn’t broken. You are left in the dark regarding the sensor and reluctor’s cooperation.
The wonderful thing about a VRT is that the signal itself should be visible as an AC (alternating current) signal as it is an analog sensor that emits a sort of sine wave. So, get a multimeter, switch it to the AC voltage measurement mode, attach the red and black multimeter leads to the signal and ground pins of the sensor, and then start the starter motor. On the multimeter, an AC signal ought should be visible. The frequency of the signal should be readable if your meter includes a “Hz button. It doesn’t matter how strong or frequent the signal is; what counts is that you should be able to see it when you turn the starter. If nothing is shown, the sensor is probably broken.
If the engine is capable of running, you can get extra points by connecting the sensor cable and then back-probing the connector to read the AC signal on the multimeter. If the engine can start and operate, you should be able to notice a rise in the signal’s strength and frequency (Hz). (Of course, there’s probably nothing wrong with the sensor if the engine can run, but that’s why it’s additional credit.)
It’s more difficult with a more recent Hall Effect sensor. Hall Effect sensors firstly need power because they are active sensors. Consequently, they are often three-wire sensors (power, signal, and ground). When the ignition key is turned, you can see if voltage is present on the power wire. Just use a multimeter set to measure voltage, connect the black probe to ground, switch the key to ignition, and check all three pins on the connector if you don’t know which wire it is, as I mentioned above. Either one of them should be 12V or 5V. If none of them are, the cable leading to the crank sensor probably has a break someplace. A resistance measurement across the signal and ground pins, however, is useless for Hall Effect sensors because they lack a coil like VRTs do.
You would need to plug in the connector, then back-probe it with the multimeter linked to the signal and ground pins while cranking the starter (since a Hall Effect sensor needs to be energized). However, the majority of meters won’t be able to detect a square wave, thus you must have a multimeter that can. Some “automotive multimeters will function and be able to measure fuel injector pulse width. Of course, an oscilloscopeeither a large bench model or a little hand-held oneis the greatest instrument of all, but few do-it-yourselfers own one.
You have it, then. This explains, at the very least, why it’s so typical for shops and DIYers to diagnose no-start problems by installing a new crankshaft position sensor and seeing what occurs, despite widespread disapproval of mindless parts switching.
Will crankshaft sensor reset after battery disconnect?
You can disconnect the battery at the negative battery terminal to reset the check engine light, then leave the car idle for an hour before reinserting the battery. This will completely drain the devices’ power and erase any short-term memory. In most cases, a damaged crankshaft position sensor will result in the car stalling out or not starting at all. Hire a skilled mechanic, such as one from YourMechanic, to come out and take a closer look at your rough idle concerns and conduct a few tests so they can provide a more individualized diagnosis and cost the necessary repairs.
Will a car start if the crankshaft sensor is damaged?
Your car’s crankshaft, as well as the one in practically every contemporary internal combustion engine, is also referred to as the crank. The part of your engine that moves your pistons up and down is the crankshaft. The cylinders on the crank’s shaft, which is arranged in an offset or squared-off zig-zag pattern to provide the pistons different push and pull timings during rotation, rotate as the crank turns. Normally, your flywheel is attached to your crankshaft to help smooth the rotation.
Even when you use a car finder with the full log of maintenance and any potential accidents, used car values can be amazing but don’t show you the potential maintenance you will have to spend money on down the road because of the wear and tear you don’t have a whole history of.
Therefore, it is better to recognize the warning signs of crank sensor problems now and check your workshop manuals than to put it off and end up with a serious engine issue later if you have an old car and fear the crankshaft might need to be replaced.
The Importance of Your Crankshaft
Given that the crankshaft in your engine moves the pistons, making it a critical part of the engine, the crank itself is crucial to the drivetrain and is required to operate your car. If your car stalls out or your check engine light comes on, there may be an issue with the sensor that timing the crank. If you keep driving once the issue gets bad, the engine could sustain serious damage.
Can I Start the Vehicle with a Bad Crank?
If the problem is only getting started, the answer to the question of whether it is safe to start your automobile when the crankshaft fails is yes. Do not operate your car if the position sensor is compromised or if you see signs of a crankshaft issue that you can’t ignore. Turn on the ignition only if the check engine light is on and there are no other significant symptoms if you want to start a car with a bad crankshaft sensor.
It’s time to send your automobile to the shop if your car has experienced a few misfires or if you’ve recently noticed uneven acceleration. If the issues are more serious, driving might seriously harm your engine and cost you a lot more to repair. What signs should you therefore watch out for?
Symptoms of a Bad Crankshaft
There are a few obvious symptoms to look for when your crankshaft begins to fail. The following symptoms are the most typical, though there may be a few others in uncommon circumstances.
Difficulty Starting Up Your Engine
The difficulty in starting your engine is the most typical indicator of a bad crank. Your car’s starting issues could be sporadic or you might not be able to start it at all.
Uneven Accelerating
Acceleration that is erratic or excessively slow is another indication that your crankshaft position sensor is not receiving the proper signal. This occurs because faulty sensor data prevent modifications to the fuel injection system or the spark timing.
Stalling
While your car’s periodic stalling is typically a sign of a wiring problem, it can also be an issue with the crankshaft position sensor. Your engine may stall if the crank position sensor has a wiring issue of its own. It can be terrifying and dangerous when your car suddenly stops in a busy intersection. Stalling out can occur when stationary at a stoplight or while moving along a highway.
Engine Vibration or Misfires
Your cylinders could be misfiring if you detect a noticeable increase in vibration in your engine. The crankshaft position sensor may be malfunctioning as a contributing factor to this problem. Your pistons’ positions could be inaccurately indicated by the sensor. You should also get your spark plug timing checked because this problem could potentially be caused by them. The crank position sensor is more likely to be the issue if the spark plugs are not the cause.
The Check Engine Light
The check engine light may come on as a result of a number of different engine problems, but it frequently does so when there are issues with the crankshaft sensor. Take your car to a professional immediately away if you have any of the additional symptoms, including inconsistent acceleration, misfires, stalling out, or trouble starting your car. To help identify the problem, the store should be able to scan for trouble codes.
How Much Does It Cost to Repair a Crankshaft?
It is not usually the cheapest fix for a car to have the crank or position sensor fixed. The price will be greatly influenced by the make and type of your car as well as your location. In some cases, labor added on top of a crankshaft repair can cost around $200. It can cost hundreds of dollars for other kinds of vehicles.
The typical cost of fixing your crank is between $280 and $400, however this cost may increase by several hundred dollars if you have a premium automobile, a difficult-to-work-on vehicle, or reside in a high-priced neighborhood.
Replacing Your Own
It is feasible to change the crankshaft sensor on your own if you are an expert at working on cars. Simply do extensive study on how to accomplish this properly and, if at all possible, how to replace one on your particular car. If the replacement is not done correctly, the issue may return or your engine may sustain more long-term harm.
Can I Wait to Fix My Crankshaft?
Avoid delaying a crank repair unless you want to spend a lot of money replacing your entire engine or purchasing a new car. A crankshaft repair may cost a few hundred dollars, but it is still far less expensive than an entire engine overhaul, which may cost several thousand dollars.
Even if you are fortunate enough to escape an accident unharmed, stopping on a motorway is exceedingly risky and will raise the cost of your auto insurance. Riding about with a malfunctioning crank may not harm your engine, but if you need to make a left turn or merge at a specific speed and your car simply won’t accelerate as it should, you put yourself and other drivers in danger.
Crankshaft Repair
Instead of putting extra miles on a defective crank and the pistons, it is cost-effective to call a towing company or roadside assistance, like AAA, if the signs of a crankshaft position sensor problem are very obvious. P0335 is the error code for a damaged crankshaft sensor. Request a “check engine light diagnostic” when you take it to the shop to be sure that is the problem and they won’t bill you for an additional, potentially needless repair.
Is a crankshaft position sensor necessary for a car to operate?
My four-cylinder 2010 Ford Escape has just returned from the mechanic. I was informed that a damaged crankshaft sensor was the reason it hadn’t been starting. The pricing was fair, and it appears that the repair was successful. But I was interested to know what this component was and why it was required.
It’s fantastic that someone identified the issue and was able to complete the necessary repairs. All contemporary automobiles have crankshaft position sensors that measure engine speed, crankshaft position, and engine speed variations. Numerous engine management operational decisions make use of speed information. The precise timing of fuel and ignition for each cylinder depends on positioning information. Additionally, variations are examined to see if misfiring is taking place.
The most crucial engine management sensor is the crankshaft position sensor; without it, the engine cannot function. Since the engine won’t produce an ignition spark, fuel injector pulses, or an engine rpm readout on the tachometer or a scan tool, it’s quite simple to determine if a sensor is malfunctioning and preventing a car from starting. Additionally, camshaft position sensors are used, allowing the management system to always know what stroke the crankshaft is in. If this sensor fails, many systems are intelligent enough to try to estimate what will happen and let the engine continue to run.
A magnetic crankshaft positioning sensor is utilized in your situation. It is the most basic of various varieties. It is situated at the front of the engine next to a toothed pulse wheel and consists of a magnet and a coil of very tiny wire. A little electrical pulse is produced as each iron tooth of the wheel comes close to the sensor’s tip. There are 35 teeth on the wheel (36 spaces with one missing). With this configuration, an indicator (missing pulse) occurs 60 degrees before top dead center for cylinders 1 and 4 and a signal pulse is sent every 10 degrees of crankshaft rotation.
A defective crankshaft sensor could result in a code.
Your dashboard’s check engine light can turn on if your crankshaft position sensor is damaged or faulty. A code between P0335 and P0338 will be displayed by a diagnostic scan tool.
How much does a new crankshaft sensor cost?
The cost to replace a crankshaft sensor ranges from $150 to $250 on average. However, if you have a higher-end vehicle, it’s not unusual for those rates to soar.
That’s because labor costs generally range from $90 to $110. Parts are what make up the remaining cost after that. There are a few crankshaft position sensors available that can cost more than $100, even though the most are priced under $100.
Thankfully for most motorists, those more expensive components are usually only found on high-end luxury cars. You can change the sensor by yourself if you want to save some money. If you can get to the sensor, the job is rather simple.
Even while you will only save around $100 by doing this, if you have a little mechanical aptitude, you can finish the entire task in less than 30 minutes.
Even though they are quite uncommon, there are some car types where the sensor can be found behind the flywheel, necessitating the removal of the gearbox in order to replace it.