Blog Bg Image

7 Symptoms Of A Bad Throttle Position Sensor

7 Symptoms Of A Bad Throttle Position Sensor

The throttle position sensor, or TPS, on your car is an extremely important part that many people have never even heard of. However, if it starts to go bad, it can have some terrible consequences that make your car unsafe to drive. So, just what is a TPS sensor and how do you know if you have problems? Here we will explore what this part does and the symptoms you need to watch for. We’ll also talk about how expensive these parts are to replace in case you need a new one. Let’s dive in!

Table of Contents

What Is A Throttle Position Sensor?

This part is exactly as the name implies if you really think about it. This sensor sends information to your car’s computer about the position of the throttle. Basically, it tells the ECM how heavily you are pressing the gas pedal. This allows the computer to control the air/fuel ratio appropriately. The harder you press the gas, the more air and fuel need to be delivered.

Once the car knows the position of the accelerator pedal, it can control the amount of air reaching the intake manifold through the mass airflow sensor. In addition, the car’s fuel injection system knows exactly how much fuel to spray into the cylinders. When these readings are off, things start to go haywire.

In older cars, this was done by mechanical parts via a wire connected from the pedal to the car’s carburetor or throttle body. As the pedal was pressed, it would open the butterfly valve inside the body to allow more air into the system. However, in today’s modern vehicles, this is done electronically. Today’s cars are much more efficient because of this.

Symptoms Of A Faulty TPS Sensor

So, how do you know if this part is bad? There are several signs that you can watch for. As you would expect, most of them relate to your car’s acceleration and engine idling. If the computer in your vehicle cannot determine where the throttle is (i.e. how much the gas pedal is pressed), then this can have severe negative effects on your engine’s performance.

 If you start to notice any of the symptoms described below, you should have your car checked out by a mechanic right away. A bad throttle position sensor can cause your car to stall or accelerate suddenly which could get you into an accident. Here are the signs to watch out for.

1. ‘Check Engine’ Light Turns On

Believe it or not, your car’s computer is pretty smart. It receives lots of data continuously from the various parts and sensors in your vehicle. If any of the data that it receives looks abnormal, then it immediately knows there is a problem. The way that it signals to the driver there is a problem is by illuminating your check engine light.

When you see your check engine light, this could point to a faulty TPS sensor. However, this warning light can also signal many other problems as well. If you notice this light come on, then you should have your mechanic check your car out to determine the cause. Most auto repair shops and auto parts stores will read the trouble codes from your computer with a scan tool for little to no cost, reset the light, and tell you what the problem is.

2. Weak/Rough Acceleration

If you notice that your car does not seem to speed up when you press the accelerator pedal, then the throttle position sensor could be to blame. A bad TPS confuses your car’s control module, and it does not know the proper amount of air and fuel that need to be delivered. If too little air or fuel is delivered, then the car will not accelerate properly. This problem may seem intermittent if the TPS has not completely gone bad. It may deliver sporadic inaccurate readings which will cause your fuel management system to go back and forth between the right amount of fuel and an improper amount.

3. Rough Engine Idle

Not only will a faulty throttle position sensor cause problems as you attempt to accelerate, but it can also give you trouble as the car idles. Even though you are not pressing the gas pedal at idle, the sensor may still be delivering inaccurate data. If the sensor is malfunctioning bad enough, your car may not even stay running at all. It can affect the ignition timing to be off, which causes misfiring and leads to your vehicle running extremely rough.

4. High Fuel Consumption/Bad Gas Mileage

This is one of the more common symptoms of a bad throttle body sensor. You might start to notice that you are filling your car up with gas more often that you previously did. This might be because your car is running too rich, which means that it is using more fuel than it needs. If your position sensor is bad and constantly reading too high, then too much fuel is being dumped into the cylinders, and this means that part of that fuel is being wasted. Poor fuel economy can point to other problems as well like bad spark plugs or dirty fuel injectors, so it is best to have a mechanic inspect your car to help determine the cause of the issue.

5. Difficulty While Switching Gears

You might notice that your automatic transmission does not shift properly, and even this could be a symptom of a faulty TPS. Automatic transmissions are extremely complicated, and the engine and transmission need to work in tandem as the car shifts gears. If the engine RPMs do not stay at the proper level during shifting, then the shifts can be clunky or seem to hang between gears. You should get this checked right away as this might also point to transmission problems.

6. Car Goes Into “Limp Mode”

Some newer vehicles have a special limp mode that allows them to run at very low performance when the engine has issues. This helps prevent further damage from being done until the issue is resolved. If your car goes into limp mode, it could be due to the throttle valve sensor. This is another symptom that you need to have checked immediately as driving your car in limp mode for an extended period of time can be dangerous for you and others on the road.

7. Car Starts Jerking

If you notice your car starts bucking or jerking, then head straight to your mechanic. This is often a symptom of a bad TPS because your vehicle is attempting to accelerate on its own. The surging you feel is a result of the readings from your sensor not remaining flat. As they start to jump all over the place, your car starts to accelerate and decelerate on a whim. You might even experience your car stalling when this happens. This is not good, and needs to be resolved asap.

Is It Expensive To Fix/Replace A Throttle Position Sensor?

While this job is not as expensive as an engine rebuild or transmission replacement, it will cost you more than some spare pocket change. The amount that you will pay depends on your specific vehicle, but you can expect it to cost you somewhere around $400 for parts and labor costs for vehicles where the sensor and mounting screws are easily accessible. On some vehicles, however, there is no easy way to get to the part. A mechanic must spend lots of time removing other pieces to access the sensor, and you might be looking at $900 or more for the repair job on these vehicles.

Is A Faulty TPS Sensor Worth Fixing?

If your vehicle is still fairly new with no other major problems, then it might be worth fixing the car. It’s not like you have a cracked engine block or something. You may be able to drive it for years to come. However, if your car is older and has other issues, it’s probably not worth sinking that amount of money into it. You would be better off getting an instant offer from Auto Wranglers. We’ll buy your car for cash, and you can even sell us a junk car. Our whole process only takes a day or two, and we always provide free towing and pickup. We serve the whole U.S., so we’ll come to you wherever you are located. Give us a call today for your instant free offer.


Faulty throttle position sensors can wreak havoc on the operation of your car, and it can even cause your car to be dangerous to drive. If you notice any of the symptoms that we’ve described, have your car repaired immediately! If you cannot afford the repair, then just sell your car to Auto Wranglers and use that money to buy yourself a new one!