7 Bad Speed Sensor Symptoms (+ Replacement Guide)

Some drivers may disregard the bad speed sensor symptoms. However, one may encounter speed sensor problems when driving. An instance is the anti-lock braking systems and traction control light which may pop up suddenly, or the vehicle may start lagging for some strange reasons.

Contemporary fuel-infused engines use several interconnected sensors to relay information to the transmission computer about the environment. The computer must know how quickly the wheel rotates and spins to keep all monitored metrics within acceptable limits.

Numerous distinct kinds of sensors can be called “speed sensors.” For example, many vehicles feature engines and transmission speed sensors, but some also have speed value sensors.

By reading this article, you will discover the many types of speed sensors, the signs of a problem, and how much it will cost to change them when it is required.

What Is an Engine Speed Sensor?

Engine speed sensors come in various designs, but they all serve the same purpose: informing the ECU where the crankshafts are at all times. Crankshaft/camshaft angle sensor (CAS), engine position sensors, camshaft, and crankshaft position sensors are different names for an engine speed sensor.

For proper ignition, engine timing is essential. For effective ignition, the ECU must know precisely when to add fuel, open your valves, then light the air-fuel mixtures. If this operation is precisely timed, the engine will perform well.

Your car might have a sensor separately for the crankshaft and camshaft position, or it might have a single sensor that can do both duties, depending on how your engine is built.

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Bad Engine Speed Sensor Symptoms

1. Start-up Problem

Engine speed sensor is integral to a car’s timing system. The ECU can’t know when exactly to shoot the spark plug if it doesn’t understand the crankshaft/camshaft positions. The vehicle may not start if defective crankshaft or camshaft position sensors.

2. Check Engine Light

Some cars feature backup sensors, which enable them to start and move even when one of the speed sensors fails. In these circumstances, you may notice check engines light with codes that should indicate which of the speed sensors is malfunctioning.

Most car parts stores offer free check engine light readings; however, if you want, you may also find a cheap code reader to be used at home.

Speed Sensor Symptoms

3. Broken Speedometer or Odometer

Speed sensors linked to your transmission power several speedometers. The speedometer might not function if these speed sensors malfunctions. In addition, many odometers, which rely on the same sensors as the speedometers, may stop working.

4. Slow or Harsh Shifting

Transmission control units (TCU), which control when and how fast the gears are changed, might need help determining speed with a speed sensor. As a result, shifts could be jerky or absent altogether.

5. No Cruise Control

For cruise control to work correctly, it needs to be aware of the car’s speed. So if one fails, you might only be able to use cruise control once the speed sensor is repaired.

6. ABS Light

A faulty wheel speed sensor could cause the ABS light to come on in cars with ABS. Some ABS systems require strong signals from the four wheels’ speed sensors to operate effectively.

If your ABS light is on, only count on the ABS to assist you if you want to use the brakes quickly. It’s advisable to take care of this problem as soon as possible to ensure that you can stop the car entirely under forceful braking.

7. Traction or Stability Control Light

You might also notice the traction and stability control lights in conjunction with the ABS light. In addition, the notification “Service Advance Trac” might appear for Ford users. The ECU needed to provide more information to determine the virtual speed between your driven wheels with accurate data from each spin.

Crankshaft Position Sensor Types

The various common varieties of this sensor are as follows. Generally, these sensors don’t need to come into contact with moving parts because they use optical or electromagnetic sensors. As a result, these sensors typically have a longer lifespan as they’re not vulnerable to wear because there is no contact between moving components.

Speed Sensor Symptoms

Variable Reluctance Sensor

Magnetic sensors, commonly referred to as variable reluctance or just variable reluctor, are analogous to the pickups in a bass or electric guitar. They use a magnet with a wire coil looped around it.

When magnetic metal objects on toothed triggered wheels pass by a variable reluctance sensor, a current flows via a wire coil within the sensor, producing a voltage. Likewise, a sine wave signal is generated when the metal goes toward the coil and away from the sensor.

Hall Effect Sensor

A magnetic field is present in a Hall Effect sensor, also known as a Hall sensor. A Hall Effect/variable reluctance sensors are fundamentally different in that the former is digital while the latter is analog.

This implies that when the metal at the front of the sensor is not moving, it still produces square waves and can detect them. An excellent illustration of a Hall Effect sensor is the crankshaft’s angle sensors (CAS) at early 1.8L Mazda Miatas.

This sensor served a dual purpose because it could inform the ECU of the location of both crankshaft/camshaft at any moment. After all, early Miatas lack variable valve timing.

Optical Sensor

Speed is measured by an optical sensor using light that passes in via a rotating disk. A square waveform is generated by optical sensors akin to the Hall Effect sensors. However, instead of a Hall Effect sensor, the 1st generation of 1.6L Miatas featured an optical CAS sensor.

What is a Transmission Speed Sensor?

The transmission speed sensor communicates with the ECU or TCU for an automated gearbox to know which gears it should be in. An input shaft speed sensors and an output shaft speed sensors are the two primary categories of transmission speed sensors.

Input Shaft Speed Sensor

The input shafts and torque converter speed, which corresponds to the engine speed, are measured by the input shaft speed sensors.

Output Shaft Speed Sensor

An output shaft speed sensor keeps track of the speed on the driveline rear after the gear ratio has been engaged. The odometer or speedometer may use this information to calculate the ground speed of the car.

What is a Wheel Speed Sensor?

The functions of wheel speed sensors include monitoring tire pressure, stability control, traction control, ground speed, ABS function, and (the speedometer/ odometer). All-wheel ECU simultaneously monitors all-wheel speed sensors. ECU can utilize this information to ascertain what is happening in the area if it observes differences in 1 or more wheel speed sensors.

Some cars have been designed to react cynically to this information. For example, most modern vehicles automatically brake wheels spinning considerably faster than the other wheel because the computer can tell that the wheel doesn’t have enough grip to move the car ahead.

The current tractions control system increases the torques that may be administered to the other wheels at the opposite side of the open degree of difference, similar to conventional limited slip differentials.

While some wheel’s speed sensor is separate devices that are simpler to replace, others are incorporated into the assembly of the hub.

Wheel Speed Sensors Replacement Cost

Some wheel speed sensor is readily available and straightforward to repair. Those sensors may be obtained for over $15 & $150 for those components alone, which makes them reasonably priced.

Luckily, most cars lean toward the lower end of the range. Prepare to pay a little bit as much for the entire hub assembly as well as the labor to mount it if your ABS sensors are integrated with the body of the hub.

The work would cost you around $200, and the assembly hub will cost you about $200.

How Does A Speedometer Work?

To provide measurements such as engine temperature, fuel level, and speed in the infotainment system, your vehicle’s speedometer sends electrical signals from its display unit back via wires into the vehicle’s interior. The VSS provides the data on which the speedometer bases its call; thus, if there’s an issue with the VSS, you will probably notice issues with the speedometer readings.

What Is the Difference Between Input and Output Speed Sensors?

Car Speedometer measurements depend on the transmission’s input/output signal. So put, a sensor inside the flywheels or drive plates of the such engine produces an input signal, which is then transmitted to either an electrical or mechanical speedometer, which displays the speed you’re in currently.

The speedometer receives data from the car’s final-drive gearbox (VSS) through a vehicle speed sensor. Acceleration sensor for a vehicle this gadget informs the engine control unit (ECU) of your car how quickly you’re traveling.

The issue with using just one of the systems to calculate your vehicle’s precise speed is that they can easily fall out of sync with one another. For example, the speedometer would begin to lag or run so fast if your2-signals are too distant.

Input Speed Sensor

An input speed sensor ensures the accuracy of the information displayed on your speedometer by sensing the degree of wheel rotation and comparing it to the number of engine revolutions in a minute (RPM). Your ECU adjusts itself to put those two figures closer together if there is a discrepancy between them.

Output Speed Sensor

An output speed sensor tracks variations in the engine RPM and relays that data to your transmission controller. Thus, it can alter gear ratios as necessary.

For example, if you eventually decide to speed when traveling at 40 mph, placing your foot on your brake, the revs will briefly reduce as the tires speed up and the car begins to move more quickly. This brief drop in RPM coincides with a rise in wheel speed detected by the output speed sensor.

It transmits this data to the TCM/ECU, which then modifies the gears to ensure no delay between the throttle position & the energy transmitted to the wheels. And that is enormously beneficial for drivers that enjoy accelerating quickly from a stop.

Both inputs and outputs speed sensors make the car’s speedometer consistent and dependable. However, as we’ve said earlier, the two signals could quickly become out of phase, resulting in inaccurate speedometer readings.

If your car’s speedometer is acting up in any way, the sensor or the wiring harness likely has to be repaired or replaced. If you need more confidence handling this yourself, it’s worth checking since repairing them typically costs far lesser when compared to replacing the complete assembly.

Ensure there isn’t anything wrong with your ABS before purchasing an input/output sensor for your car, as this checks and regulates them. Your input/output speed sensors checker can always be used to pinpoint the exact location of the issue.

Can a Faulty Output Speed Sensor Prevent a Vehicle From Shifting?

A car may be unable to move if its speed sensor is malfunctioning. This is significant because a malfunctioning speed sensor can create a disparity between the data the computers are reading and what is happening mechanically.

A speedometer must be adjusted so the transmission ECU knows how much to shift and when to shift. The signs will show an ability to pick gears or run at one load but not the other once you keep switching.

Sometimes, even when you’re in gear, it’s likely for your vehicle to feel it’s normal, which could cause the driver to assume their vehicle is going through something else from what technicians see during an examination.

Speed Sensor Troubleshooting

Some methods you may try to fix your speed sensor if it needs to be fixed. Here are some suggestions for diagnosing a malfunctioning speed sensor:

Check to wire

An electrical fault is one of the most frequent reasons for speed sensor issues. Therefore, it’s crucial to inspect the wiring first if you suspect that your speed sensor might be defective. Ensuring that all of the connections at the sensor are solid can help you do this.

Clean Sensor

Your sensors can become blocked with debris and dirt, leading to problems. Try cleaning the sensor using compressed air or a brush when you feel that this might cause the issues.

Replace Sensor

If you’ve tried all, but nothing is responding, the speed sensor might need to be changed. You’ll need a few simple hand tools and an hour to replace the sensor.

To get your old sensor, you’ll need to disconnect some components from underneath the car, but once you’ve done that, swapping out the old sensor with a new one shouldn’t be a problem at all. The best action is to have a technician immediately fix the issue if neither of these suggestions works for you.

The last thing you will do is allow this problem to persist for too long since having a defective speedometer or accelerating problems can have many adverse effects.

How Do I Know If My Speed Sensor Needs To Be Replaced?

It’s about time for a change if you’ve tried troubleshooting your sensor, yet nothing has happened. Most of the time, you can accomplish this on your own with a few straightforward hand tools.

The repair should barely take one hour to finish. So what Possible Repercussions Might There Be If a Speed Sensor Isn’t Working? The effects of malfunctioning speed sensors in your vehicle might range in severity. These consist of the following:

Incorrect Speedometer Readings

When you do not have a working sensor, the speedometer will only function properly. It’s essential to fix the issue as quickly as possible because doing so could lead to an accident.

Bad Acceleration

If the vehicle hesitates or struggles to move at your speed, there might be a problem with its acceleration system. Before deciding to have a new speed sensor fitted, try analyzing the situation and changing any faulty parts.

Speed Sensor Replacement Cost

The price of engine and transmission speed sensors varies based on the kind of sensors. Costs for crankshaft and camshaft position sensors range from $15 – $250. Components from aftermarket manufacturers are frequently less expensive.

The price of transmission speed sensors is typically comparable. The amount of labor required differs by engine type because specific sensors are easier to find than others. You should expect to pay between $800 and $1,000 if your technician wants to drop the transmission to change the transmission’s sensor.

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Frequently Asked Questions ­- Speed Sensor Symptoms

Can you drive with an alarming speed sensor?

Driving with a faulty speed sensor ultimately puts not just your safety but also the safety of your vehicle in danger. If you believe they are broken, you should have the speed sensors repaired as quickly as possible. What makes speed sensors malfunction? Your transmission speed sensors can eventually become defective owing to wiring problems or fail as a result of being used repeatedly whenever you drive your car. If the magnetic sensor malfunctions due to iron adhering to the sensor tip, an incorrect reading will result.

What do speed sensors do?

The speed of the vehicle sensor (or VSS) gauges either wheel speed or transaxle/ transmission output. The ECM uses this data to start diagnostic procedures to change engine parameters like air/fuel ratio, transmission shift point, and ignition timing. Can a poor speed sensor result in power loss? A car’s power is lost if the speedometer sensor is among the several EFI sensors to determine how much fuel to give the engine. So if your vehicle begins to lose power, specifically when you push on the throttle, a broken or inoperable speedometer sensor may be to blame.

Can an alarming speed sensor cause loss of power?

The car’s power is lost. The speedometer is among EFI’s sensors to determine how much fuel the engine gives. So if your vehicle begins to lose control, mainly when you push on the throttle, a broken or inoperable speedometer sensor may be to blame.

How much does it cost to replace a speed sensor?

Car speed sensor repair typically costs around $280 & $325. While components are priced at around $163 to $177, the labor cost is predicted to range from about $117 to $148. Taxes and other fees are not included in this range, nor are your particular vehicle or geographic area taken into account. Therefore, there might be more repairs required.

How many speed sensors does a car have?

Two (2) transmission speed sensors, one at each shaft’s input and output, are standard features in modern vehicles.

Can a vehicle speed sensor be cleaned?

Once the sensor is removed, use your rag to clean it well. I avoid using chemicals on my sensors to prevent any possible issues. Therefore, rinse your sensor well after using a mild soapy water solution if your sensor is filthy. In a primitive setting, the ABS sensor is a precise instrument.

Does the speed sensor affect the RPM?

Your car’s transmission can only change effortlessly with available speed sensors. These sensors keep track of a transmission’s inner rotations. As a result, after receiving the data and determining the turning speed, the transmission control unit performs the required modifications.

Will a speed sensor throw a code?

The transmission speed sensors monitor the input/output shaft speeds, which also contribute to your cruise control monitoring. Your powertrain control module (PCM) would send an error code to your car’s ECU when the sensors on your vehicle, truck, or SUV cannot provide reliable information to the onboard computer.

Which speed sensor controls the transmission?

Does this speed sensor control your transmission? Two sensors usually transmit this data to the car’s power train control module. The input sensor, the first, keeps tabs on the input shaft speeds of the transmission. The output sensor, the second sensor, keeps track of the output shaft speed.

Conclusion – Speed Sensor Symptoms

Although it’s technically possible to drive your vehicle without a properly functioning vehicle speed sensor, this move is strongly discouraged. A bad VSS can have multiple negative impacts on aspects of vehicle operation—which is the more reason you should replace a bad speed sensor as soon as possible.

So, with these we’ve come the end of this piece. Trust you had something to part with.

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