How to Detect Engine Speed Sensor Problems

An engine speed sensor, also known as a vehicle speed sensor, retrieves and sends data to your car’s computer system. A car speed sensor shows the car’s engine spinning rate. The vehicle speed sensor does this by taking note of at what rate the crankshaft is spinning. If there are some engine speed sensor problems, it may lead to other difficulties in your car.

What Does A Speed Sensor Do In Your Car?

Before going far, let’s find out about the function of an engine speed sensor. A speed sensor is a device in the engine management system that measures the vehicle’s current velocity. The mechanism of this sensor is monitoring the rotation of the crankshaft which is responsible for turning the engine’s piston and generating the power. After that, it will send the signal to the car’s engine control unit (ECU) which processes the information to make the decision about the engine’s speed and position. Specifically, the ECU will determine how much fuel will be injected into your cylinders to reach maximum performance.

We can see that the speed sensor plays a critical role in the engine system, it helps your engine run smoothly and efficiently, besides, it also could help to diagnose and troubleshoot when the car engine has any problem. As issues with the speed sensor, it will cause a range of symptoms that you can easily observe visually.

Most Common Signs of Engine Speed Sensor Problems

A defective car speed sensor symptoms may cause different problems. The symptoms of a bad transmission speed sensor are the same as some other engine problems, like a bad throttle position sensor or faulty coil pack. Below is a list of some of the most common signs of a defective engine speed sensor gathered by Car From Japan‘s car bloggers.

1. Harsh or improper shifting

When there are symptoms of a bad transmission speed sensor – is also known as an output of the speed sensor. It is an important component in a vehicle’s transmission system. It measures the rotational speed of the output shaft and sends this information to the vehicle’s computer or transmission control module. If the transmission speed sensor is not working properly, it can cause a range of problems with the vehicle’s transmission system.

At that time, the powertrain control module could not control the shifting of gears within the transmission properly.  This may cause transmission revs high before shifting gear or leading to late transmission overdrive and inability to go into that top gear. Harsh shifting may damage internal components such as valve bodies, hydraulic lines, and even mechanical gears in some cases.

2. Inactive cruise control

The transmission speed sensor does not only control the input and output shaft speed, meanwhile, it also plays a role in monitoring the cruise control. As we know, the speed sensor provides information to the cruise control system about the vehicle’s speed, and if it is not working correctly, the system may not be able to maintain a consistent speed. When there are some engine speed sensor problems, an error code will be sent to the car’s Engine Control Unit (ECU). Then the cruise control will be shut down and does not engage when you press the button. The speedometer also may work frantically or sometimes stop working altogether.

SEE MORE:

• The Cost of Brake Drum Replacement
• 6 Most Common Crankshaft Position Sensor Symptoms

3. Check engine light comes on

The Check Engine light is an error signal for the engine system, including the speed sensor.

Meanwhile, the ECM directly receives information from the sensor, processes it, and sends it back to control the operation of the brake system and engine system. When the ECU detects that information is mistaken from the normal one or there is no signal, the Check Engine Light will immediately light up the light to notify drivers. Then the check engine light comes on sporadically and intermittently when accelerating. The overdrive light also may go ‘On’ or ‘Off’ for no apparent reason.

At this time, drivers should give the vehicle to the repair center to fix it to avoid serious danger. In particular, the case of the Check Engine light flashing continuously is an emergency warning that the engine is having serious problems and needs urgent fixing. If it is not possible to immediately repair, the driver should only move at a maximum speed of 40km/h to avoid danger.

Watch this video to learn more about the symptoms of a bad engine speed sensor:

How to Look for Problems in the Vehicle Speed Sensor

If you notice any of the above-mentioned symptoms, you should have your car checked at a nearby auto repair shop. While the problems may be transmission-related, run a complete computer diagnostic test at a repair shop, instead of directly taking your car to a specialty shop.