How Long Can You Drive A Car With A Bad Speed Sensor?

How Long Can You Drive A Car With A Bad Speed Sensor – In the intricate dance of car mechanics, sensors play a pivotal role in ensuring everything runs smoothly. Amidst the array of sensors that keep vehicles ticking, one fundamental component stands out: the speed sensor.

Driving a brand-new model or a reliable old vehicle, the speed sensor remains a crucial part of your car’s functionality. Situated within the transmission system, this sensor diligently measures output, providing essential data that orchestrates the seamless coordination of engine performance and assists driver-centric systems like the ABS.

But what happens when this unassuming yet critical sensor fails?

How Long Can You Drive A Car With A Bad Speed Sensor

When the speed sensor calls it quits, its impact reverberates throughout the vehicle. Suddenly, accurately gauging your speed becomes a guessing game, and this disruption can wreak havoc on both the performance and safety of your car.

So, just how long can you safely navigate the roads with a malfunctioning speed sensor?

Fortunately, driving with a bad speed sensor isn’t an immediate red alert. You can typically go a few days without facing major issues. However, here’s the catch: procrastination is not your ally here. Ignoring a faulty speed sensor isn’t a wise choice.

The longer you delay addressing this issue, the more havoc it might wreak on your vehicle’s efficiency and longevity.

Decreased fuel efficiency and sluggish acceleration are just the tip of the iceberg when it comes to the consequences of a malfunctioning speed sensor. Left untreated, this seemingly minor issue can snowball into more significant and costly complications down the road.

The question lingers: How far or how long can you drive with a bad speed sensor? The answer hinges on urgency and responsibility. While a few days might pass without immediate repercussions, prompt attention to this problem is imperative for safeguarding your car’s health and your safety on the road.

How Long Can You Drive A Car With A Bad Speed Sensor

What Is a Speed Sensor?

A speed sensor is like a secret spy that keeps an eye on your car’s speed at all times. It’s an essential electrical component that is attached to your car’s transmission, and its main job is to measure how fast your car is going.

This sensor, known as the vehicle speed sensor (VSS), collects important data that your car uses in a variety of ways.

For instance, when your car is being diagnosed with any problems, the VSS provides valuable information that helps identify issues.

Additionally, the speed sensor plays a crucial role in improving your engine’s performance. By gathering data about your car’s speed, the VSS allows the engine to make necessary adjustments in areas like ignition timing and the air-fuel ratio.

This helps your car run more efficiently, maximizing fuel usage and reducing emissions.

Wheel Speed Sensor vs Vehicle Speed Sensor

You may be wondering about the difference between a wheel speed sensor and a vehicle speed sensor. Well, a wheel speed sensor does exactly what it sounds like – it measures the actual speed of your wheels.

This information is then sent to the Engine Control Unit (ECU), which uses it to control features like the anti-lock braking system (ABS) and traction control.

On the other hand, a vehicle speed sensor (VSS) measures the speed of your car’s transmission or transaxle output. It provides the car’s computers with accurate data to ensure efficient engine performance and the proper functioning of driver-assist systems.

So, while the wheel speed sensor focuses on the speed of your wheels, the vehicle speed sensor focuses on the speed of your car as a whole. Both sensors are essential for safe and optimal driving, and it’s important to understand their differences to effectively diagnose any issues you may encounter on the road.

How Do Speed Sensors Work?

Ever wondered how your car knows exactly how fast it’s going? Well, that’s thanks to a small device called a speed sensor. The vehicle speed sensor (VSS) measures the rotational speed of your car’s wheels and sends that information to the engine control unit (ECU).

The ECU uses this data to determine things like fuel injection, spark plug timing, and gear shifts, ensuring your car runs at its best regardless of speed or load.

The VSS works by using magnets and an electronic sensor. The magnets are attached to the wheel hub, while the sensor is mounted on the transmission or differential.

As the wheel spins, it passes by the sensor, generating a signal that is then sent to the ECU.

But why is a functioning speed sensor so important? Well, without one, your car would be clueless about its speed and would go into a “limp mode.” This means reduced performance, fuel economy, and increased emissions. In some cases, it could even lead to engine damage.

How Long Can You Drive with A Faulty Speed Sensor?

Can I drive with a faulty speed sensor? Technically, yes. Your car will still be able to move even with a bad speed sensor. However, this doesn’t mean you should ignore the issue. Driving with a faulty speed sensor comes with increased risks.

Without an accurate measure of your speed, you may not be able to react quickly in certain situations, putting yourself, your passengers, and others on the road in danger.

Additionally, a bad speed sensor can lead to decreased fuel efficiency and poor acceleration, impacting the overall performance of your car.

What Are The Symptoms Of a Bad Speed Sensor?

Understanding your vehicle’s health is paramount for smooth and safe travels on the road. Among the myriad components that keep your car functioning optimally, the speed sensor stands as a silent guardian, often unnoticed until something goes awry.

Recognizing the symptoms of a malfunctioning speed sensor (VSS) can be pivotal in averting potential issues and ensuring your vehicle’s efficient performance.

1. Check Engine Light Turns On

A glaring signal that often catches a driver’s attention is the illumination of the Check Engine light on the instrument panel. While this indicator can signify various malfunctions, it shouldn’t be disregarded, especially when paired with other symptoms linked to the vehicle speed sensor.

2. The Speedometer Behaves Erratically

A reliable speedometer serves as the driver’s interface for monitoring the vehicle’s speed. When the VSS falters, it disrupts the flow of accurate data to the speedometer, resulting in erratic behavior.

Witnessing erratic speedometer readings often indicates an underlying issue with the transmission speed sensor.

3. Torque Converter Clutches Aren’t Utilized

In automatic vehicles, the torque converter clutch relies on precise speed data from the VSS to engage at predetermined speeds.

When the VSS fails, the connection between the gearbox and the engine can be compromised, leading to the malfunction of torque converter clutches.

4. Cruise Control Dysfunction

An overlooked yet telling sign of a problematic VSS is the malfunction of the cruise control feature. As this system relies on accurate speed information, a faulty speed sensor disrupts its functionality.

Most vehicles are programmed to disable cruise control when erratic or no data is received from the VSS.

Recognizing these symptoms individually or in combination serves as a red flag, signaling an impending issue with the speed sensor. Prompt attention and addressing these warning signs are crucial to prevent potential complications that may arise from a malfunctioning speed sensor.

Problems With a Bad Speed Sensor

The intricate network of sensors within modern vehicles ensures seamless operations and safety features, with each component playing a crucial role.

Among these, the speed sensor (VSS) stands out as a linchpin, dictating not just speed readings but also influencing various driver-assist systems and overall vehicle performance.

Understanding the repercussions of a malfunctioning speed sensor is vital for maintaining safety and optimal functionality.

Safety Issues

When a vehicle’s speed sensor fails, it doesn’t just disrupt speedometer readings; it poses significant safety concerns. Driver-assist features, reliant on accurate data from the VSS, become compromised.

Consequently, automated safety mechanisms might misinterpret speed inputs, leading to erratic responses.

For instance, automatic braking systems could engage prematurely or with excessive force, potentially causing accidents instead of preventing them.

Performance Issues

Beyond safety implications, a malfunctioning speed sensor severely impacts the vehicle’s performance. The transmission system heavily relies on precise speed data from the VSS to function smoothly.

When this sensor fails, it disrupts the transmission’s operation, resulting in rough gear changes and extended intervals between shifts.

This inefficiency not only affects the driving experience but also accelerates wear and tear on crucial components.

How Much Does It Cost to Replace a Speed Sensor?

How much will it set you back to replace a speed sensor? Well, the good news is that a speed sensor replacement can cost under 200 Aussie dollars. However, keep in mind that there might be an additional charge for labor if you decide to seek the help of a mechanic.

But if you’re a handy do-it-yourself enthusiast, you might be able to replace the speed sensor yourself. Just be sure to have the necessary knowledge and tools to do the job safely and effectively.

If not, it’s always safer to let your trusted mechanic take care of it for you. Remember, your safety on the road is priceless, so don’t skimp on getting that faulty speed sensor replaced.

Causes of Bad Speed Sensors

The seamless operation of a vehicle’s speed sensors is crucial for accurate speed readings and the proper functioning of various vehicle systems.

Identifying the root causes behind malfunctioning wheel speed sensors is imperative in maintaining optimal vehicle performance.

Let’s delve into the underlying factors that lead to the failure of these critical components.

Causes of Bad Speed Sensors

Physical Damage to the Sensor

One of the primary culprits behind malfunctioning speed sensors is physical damage. Continuous usage can cause the plastic housing of the sensor to become brittle over time.

Moreover, the magnetic component within the sensor is susceptible to wear and tear, leading to potential breakage.

Electrical Faults

Speed sensors operate based on electrical signals. Internal electrical faults can disrupt the transmission of accurate signals, resulting in erratic readings or no signal at all.

The identification of such faults often requires diagnostic tools like analyzers or voltmeters.

Lack of Proper Maintenance

Neglecting routine vehicle maintenance can significantly impact wheel speed sensors. Accumulation of debris, particularly old transmission fluid impurities, can hinder the performance of the magnetic pickup or the grooved wheel, impeding their ability to provide accurate readings.

Dirt or debris accumulation on the sensor can interfere with its transmission of electrical signals to the vehicle’s computer, leading to inaccurate speed readings and hazardous driving conditions.

Defective Hardware

Hardware failure within the sensor or damage to the wiring connecting it to the vehicle’s computer can cause erroneous speed sensor signals.

Due to an inherent defect in the sensor or damage to its wiring, rectifying this issue typically involves replacing the faulty sensor.

What happens if I disconnect the speed sensor?

If the speed sensor is disconnected, it will primarily affect specific functions associated with the vehicle’s speed readings. Notably, the speedometer’s functionality might cease, although the starting process of the vehicle remains unaffected in most cases, especially if the sensor isn’t tied to critical safety functions.

Approximately 95% of the time, disconnecting the speed sensor won’t hinder the car’s ability to start.

What happens when a wheel speed sensor goes bad?

When a wheel speed sensor malfunctions, it sends erroneous data to the Anti-lock Braking System (ABS) control module. This false information can mislead the ABS module into perceiving a skidding situation, triggering the activation of the anti-lock brakes.

Consequently, the ABS will release brake pressure, causing rapid and intermittent braking, potentially affecting the vehicle’s handling.

Can I replace a speed sensor myself?

Replacing a wheel speed sensor is generally straightforward and can be done by oneself. It typically requires around an hour at most to complete.

Additionally, it’s possible to remove the ABS wheel speed sensors independently without disassembling other components integrated into the wheel bearing hub assembly.

How often do speed sensors go out?

Speed sensors, particularly transmission output sensors, have a lifespan typically ranging between 30,000 and 50,000 miles. However, their longevity, similar to brake pads or other vehicle components, is heavily influenced by driving conditions.

Factors such as driving habits, road conditions, and maintenance practices significantly impact the lifespan of a speed sensor.


Driving with a bad speed sensor is not worth the risk. While you can technically drive with a faulty speed sensor for a few days without major issues, it is important to address the problem as soon as possible.

Ignoring a malfunctioning speed sensor can lead to decreased fuel efficiency, poor acceleration, and potential damage to the engine.

Plus, it puts you, your passengers, and other road users at an increased level of risk.

So, can you drive with a bad speed sensor? Yes, but it’s always better to prioritize your safety and have the sensor replaced promptly. Don’t compromise your peace of mind and get your car back to optimal performance by addressing this issue promptly.

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