Does the ‘check engine’ light in your car keep going on and off for no apparent reason? Has your speedometer ceased to move? Are you having difficulty controlling the speed of your car?
If the answer to any of those questions is ‘yes’, you may have a problem with your transmission speed sensor.
Speed sensors are, simply put, devices used to track a vehicle’s speed. It, along with other components, is what allows the speedometer to work on your car. The physical location of a speed sensor is usually in the transmission housing which is near the passenger seat at the front.
Some speed sensors also provide assistance to the anti-lock braking system (ABS) by checking wheel speed and forwarding the data to the car’s control system in order to help the driver handle the steering better.
Transmission Speed Sensor Replacement Cost
When identifying the price of transmission speed sensor replacement, as with most automobile parts, the price will vary depending on the year, make, and model of the car.
A vehicle speed sensor price can range from as low as $5.06 to as high as $1,797.15. The price varies because there are many different types of speed sensors, with some being manufactured specifically for certain vehicles.
Here’s an example: a Motorcraft vehicle speed sensor for a 2018 Ford Fusion 2.0L costs $455.22, but the exact same brand and part for a 2009 Ford Fusion 2.3L only costs $137.29. As you can see, newer models tend to have higher prices for parts.
Here’s a list of the price ranges of vehicle speed sensors for some of the most well-known brands:
- ATP: $16.48 – $72.85
- Beck Arnley: $25.49 – $197.89
- Crown: $12.89 – $65.49
- Delphi: $17.57 – $49.41
- Febi: $5.06 – $262.34
- German: $77.15
- Mopar: $28.12 – $221.97
If you bring your car to a repair shop, there will be an extra labor charge to factor in the total amount.
An automobile technician’s fee varies depending on the shop, but it’s generally around $70 – $200.
An alternative to bringing your car to the repair shop is to replace the speed sensor by yourself. It’s a relatively easy process even if you haven’t had much experience with fixing cars.
What is A Transmission Speed Sensor?
Transmission speed sensors, also known as vehicle speed sensors (VSS), are used to calculate a moving car’s speed for automobiles using an automatic transmission. Cars using manual transmission do not typically use modern types of speed sensors as the gears are switched manually using the gear shift.
These sensors are a very important part of newer cars and failure of the sensors can cause a variety of problems.
There are two sensors involved – the input speed sensor (ISS) and the output speed sensor (OSS). These sensors are connected to the crankshaft of an automobile’s engine and measure how fast it rotates in order to determine the overall speed of the vehicle. They record all pertinent information and then send it to the car’s computer.
Using the information received from the sensors, the car’s computer then checks how fast the crankshaft is spinning and uses the data to figure out whether the gear needs to be switched higher or lower and makes the appropriate selection automatically. The transmission will fail to work properly if either the ISS or OSS sensors experience an electrical issue or become misaligned.
If a sensor experiences a problem, it will make a mistake and send incorrect data to the car’s computer. This results in misalignment of the gears. The computer will automatically detect any inconsistencies and alert the driver by turning on the “Check Engine” light. An error code will also be assigned which can be analyzed using a special device called a Car Code Reader.
The speed sensor on a car also performs a variety of other useful functions. It is used by a car to determine when the anti-lock braking system should be activated.
Symptoms of a Failing Speed Sensor
Vehicle speed sensors that have become faulty can cause a multitude of problems. A failing sensor is sometimes difficult to identify right off the bat as the symptoms are often the same as other car problems such as defective coil packs and misaligned throttle position sensors.
Here’s a list of the most common symptoms that can help you at least get an idea if the transmission sensors are going bad.
- While driving, you might hear the transmission revving higher prior to the gear changing on the dashboard interface.
- The overdrive light on the dashboard may blink on or off intermittently.
- The speedometer needle may move erratically or not at all.
- When switching into overdrive, the transmission will be noticeably late.
- The vehicle may be incapable of switching to the highest gear.
- While driving, the check engine light may intermittently turn on or off.
- Since the car’s computer is unable to receive any correct data from the sensors, the transmission will not shift gears properly. The gears may shift faster, slower or rougher than usual. Since an automatic car transmission uses hydraulic control, this intermittent shifting can cause damage to other car parts.
- A car’s cruise control might shut down as a response to the main computer receiving incorrect signals from the vehicle sensors.
- The odometer on the car may also not be functioning correctly.
Additionally, if you have a Car Code Reader, you can quickly and easily determine if the problem is with the speed sensors or other car components. A car’s computer will assign specific error codes which can be scanned, read, and which will identify which sensor is affected.
If the check engine light turns on, any of the following codes may present themselves: P0720, P0721, P0722, and P0723.
Without a Car Code Reader, you won’t be able to identify the specific issue and a car must be taken to a repair shop to be serviced by a mechanic. Local repairmen can scan the error codes and find out why the check engine light is turned on. Once the problem is fixed, the codes will be reset.
Possible Reasons Why Speed Sensors Go Bad
Vehicle speed sensors can stop working for a few possible reasons. Transmission speed sensors are located at the end of the transmission which exposes them to high levels of heat.
The sensors are generally well-protected from external elements. But in some rare cases can become dirtied or contaminated by water and debris. They can also become tainted by dirty lubrication grease or other materials located inside the housing.
The most common type of damage that a sensor experiences is wiring damage. In most cases, the sensor itself isn’t the problem but the electrical wires that are connecting it to the transmission.
These wires are somewhat exposed on the underbelly of a car and therefore at the mercy of dust and dirt. Continuing to drive with a bad speed sensor will reduce your car’s performance and possibly lead to other car parts being damaged.
Not only that, but some systems such as the speedometer and the anti-lock braking system can completely die if a faulty transmission speed sensor isn’t replaced immediately.
How to Prevent A Speed Sensor from Going Bad?
The best preventive measure to take is to have your car checked by a mechanic as soon as you begin to experience symptoms indicating a potential issue with the speed sensor. Sensors can easily be revived by simply fixing a loose wire or cleaning off excess dirt and crud.
Before passing your sensor off as dead, bring it in and you might not need to have it replaced. You can also visually inspect it yourself if you know how. Steps are included in the next section that can help you accomplish this.
Besides that, you may try cleaning it out, especially if you’ve been driving through any wet and dirty terrain. If you still have the owner’s manual for your car, take a look at it and figure out where the speed sensor is located.
Most sensors have a housing to keep it securely attached to the chassis. Once you locate this housing, simply unscrew it to view the sensor inside. Use a clean and dry cloth to gently wipe out any dirt and debris that you find inside.
Use electrical tape to fix frayed, damaged or loose wires. If it doesn’t fix the issue, you’re going to end up bringing the car in anyway, so it’s worth a shot. When replacing the housing screws, don’t turn them too tightly or they might break.