What are knock sensor functions and symptoms?

The Function

The main function of a vehicle’s knock sensor is to sense for vibrations that are caused by the detonation or knock of the engine. You will find the knock sensor on the intake manifold, the cylinder head or the engine block. Once there are vibrations sensed, the powertrain control module receives a voltage signal and uses it to change the timing of the ignition and stop it from detonating. By doing this, the engine will be protected from being damaged during pre-ignition.

Remember that denotation in an engine is basically when fuel explodes in its cylinder and alters the timing of the ignition.

So if the knock sensor fails then this detonation cannot be regulated and will result in huge damage to your engine. That is why it is important to recognize what the symptoms are of a failing knock sensor. Then you can replace it and avoid paying thousands of dollars fixing a damaged engine.

The Symptoms

When a knock sensor goes bad, the symptoms will usually be noticeable when you’re going at high speeds like on the interstate. The acceleration and fuel mileage will start to decrease for one thing. Also, your car’s computer system should notify you when there is a problem with the knock sensor. Either that or you’ll see the “check engine” light flashing on your dashboard. In rare circumstances, cheap or dirty gasoline will improperly cause the powertrain control module to falsely warn you that you have engine problems when you really don’t. So if you really want to be safe about this then you can use super unleaded gasoline instead of regular unleaded.

Aside from warning lights, you can also listen for noises that indicate a failing knock sensor. These will be thumping sounds that will come directly from the engine. As the knock sensor gets worse, the thumping sounds will gradually get louder and louder. This noise occurs because the air and fuel ignite in the cylinder rather than getting to the combustion point.

Other symptoms include an engine misfire when trying to start the engine or even vibrating and shaking too. You may even see strong exhaust fumes emitting from the engine which gives off a burning smell in the car. Again, this is from the denotation of air and fuel in the cylinder. The worse symptoms will involve the car jerking, hesitating or dragging while in motion. Don’t let it get to this point. Listen for the early warning sounds and then take your car to an auto repair shop to get new knock sensors.

5 Symptoms of a Bad Throttle Position Sensor

The throttle position sensor transmits the information about the position of your throttle to the computer of your car which is commonly known as ECM (electronic control module). The throttle position sensor consists of mechanical parts and is prone to wear and tear.

A bad throttle position sensor will feed wrong input values to your car’s computer and will usually result in poor fuel economy. The throttle position sensor does this by reading the position of the acceleration pedal and reporting it to the ECM. The ECM uses this data to control the remaining throttle body which is an important part of the air intake system of a car. Without a properly functioning throttle position sensor, the ratio of the air-fuel mixture of the engine will be compromised which will result in the problems for the car to run smoothly.

Common symptoms of faulty throttle position sensor

Here are some of the symptoms which can help you identify a faulty or malfunctioning throttle position sensor.

Engine Random Stalling

If your vehicle stalls randomly, then it shows another clear sign that the throttle position sensor of your car is going haywire. This stalling may occur whether in idle position of the car or in the driven state. The stalling problem is also associated with some other problems as well, but if it occurs in combination with any other of the symptoms or if it turns into a regular development, then the throttle position sensor on your car will need to be looked at.

Delayed Acceleration/Jerking

If your vehicle is expressing the signs of delayed acceleration when you press the gas pedal or if it is showing the signs of jerking, then you may have a faulty position sensor at your hands. The delayed acceleration is that there is a slight delay between the you gas pedal pressing time and the time your car begins to accelerate. Similarly, if your car begins to jerk, stumble or hesitate during the acceleration, the throttle position sensor is likely to be the culprit.

Engine Speed Increases

If you any sudden surges in speed with driving on a constantly pressed gas pedal, it is a clear sign that the throttle position sensor of your is malfunctioning. These speed surges can occur when you are driving on a highway and your vehicle will increase its speed by itself. Take it to a mechanic straight away if these symptoms show up in your car.

Problems Switching Gears

If you feel that you are having trouble in switching the gears of the your car either when speeding up or when slowing down, then it is a clear indicator that the throttle position sensor of our car is not doing so well. If you notice this symptom alone, then that could mean that this is a fault in the transmission of the vehicle, but if you have already noticed the problem with acceleration, then you can be pretty confident that the throttle position sensor on your car has been messed up.

DTC or Engine Code Light On

One of the potential reasons behind the lit up check engine light is a bad throttle position sensor. Usually the DTC is showing: P0120 (Throttle Position Sensor/Switch ”A” Circuit Malfunction). You may try to look into the cause of the light yourself, but it is always recommended to take it to a mechanic straight away so that the problem can be verified.

A faulty throttle position can pose potential danger to you and your vehicle if the repairs are not made right away.