Throttle Position Sensor Reset: Everything you need to know.

A lot of people have asked me if they should perform a throttle position sensor reset when their car starts to idle like crap or hesitate when accelerating. Here is the simple answer: you can’t reset a throttle position sensor. You probably just need to replace it. 

Allow me to explain…. 

What is a throttle position sensor?

A throttle position sensor (TPS) is a sensor (duh). 

By definition, a sensor is a device that detects or measures a physical property.

Your TPS measures the speed and position of your car’s throttle body butterfly valve. (This is the valve that controls how much air is fed into your engine). The more you press on the gas pedal, the more the butterfly valve opens.

Your throttle position sensor is connected directly to the butterfly valve. When the butterfly valve moves, a small dial inside of the TPS moves too.

The throttle position sensor sends the information it is collecting to your car’s on-board computer. So it’s basically telling your car’s computer how far open the butterfly valve is.

Bottom line, you can’t do a throttle position sensor reset because the sensor is just a little dial that keeps track of the position of your throttle body butterfly valve. It’s not a sophisticated piece of equipment that requires programming.

OK Now What?

Now that you know you can’t reset your car’s throttle position sensor, I’ll tell you a bit more about throttle position sensors and help you figure out if your throttle position sensor is the reason why your car is running like crap.

You’ll learn why your car has a throttle position sensor, how it operates, and potential problems that may arise when a TPS becomes faulty. 

If your check engine light turns on because of a bad throttle position sensor, I’ll tell you what the possible OBD codes are and what they mean.

And finally, I’ll explain how much it costs to replace a throttle position sensor and if you can do it yourself.

Purpose of a Throttle Position Sensor

Your throttle position sensor keeps track of (you guessed it!) your throttle position. This little sensor sends the data about your throttle position to your car’s on-board computer (AKA engine control unit (ECU).

The ECU then uses this data to adjust things in your car like ignition timing, fuel delivery, and emissions control…. Which makes your engine run smooth like buttah.

A throttle position sensor is essential for precise air delivery and therefore engine management.

How a Throttle Position Sensor Works

A throttle position sensor is basically a variable resistor that detects the position of the throttle valve and converts the position into an electrical signal. This signal is then sent to your car’s ECU.

Typically, a throttle position sensor consists of three main components: a housing, a sensing element, and a wiring harness. 

The housing is usually made of plastic or metal and is attached to the throttle body, while the sensing element is the variable resistor that transforms the throttle valve’s position into an electrical signal. 

The wiring harness is the link between the sensor and your car’s ECU.

In most cases, the throttle position sensor operates within a specific voltage range, often between 0.5 and 4.5 volts. 

As the throttle valve opens or closes, it causes a change in the voltage signal provided to the ECU. 

This allows the ECU to accurately determine the throttle’s precise position and adjust the engine’s parameters accordingly.

Holy crap! That was a lot.

If all of what you just read was a little confusing, check out this video. The guy in the video does a way better job of explaining it and visually shows how things work with actual parts.

Symptoms of a Bad Throttle Position Sensor

Some symptoms of a bad throttle position are:

  • Hesitation on acceleration
  • Rough idle
  • Reduced fuel economy
  • Check engine light

Without the information from the throttle position sensor, your car’s ECU doesn’t know the position of your throttle body butterfly valve. 

When this happens, your car can’t set the correct fuel mixture or ignition timing.

Basically, your car’s computer gets all confused and doesn’t know what to do. So your car runs like crap. 

Think about it this way… Your throttle position sensor delivers critical data to your car’s ECU (brain) so that it can run smoothly.

Similarly, your eyes deliver data to your brain (your ECU, lol) so that you can walk without bumping into things. 

If your eyes are covered, you can’t see and therefore can’t walk smoothly.

And without a TPS, your car can’t “see” how much air is being sucked into the engine and therefore can’t run smoothly.

Does this make sense? Good!

Check Engine Light and Trouble Codes

If you have a bad throttle position sensor, your check engine light will likely turn on.

Common trouble codes thrown for a bad throttle position sensor are P0120, P0121, P0122, P0123, and P0124. If any of these codes appear, you most likely need to replace your throttle position sensor.

And no, none of them mean you need a throttle position sensor reset! Remember, resetting your TPS isn’t possible.

Here’s a quick summary of what each throttle position sensor code means

  • P0120 – Throttle Position Sensor A Circuit Malfunction
  • P0121 – Throttle Position Sensor A Circuit Range/Performance Problem
  • P0122 – Throttle Position Sensor A Circuit Low Input
  • P0123 – Throttle Position Sensor A Circuit High Input
  • P0124 – Throttle Position Sensor A Circuit Intermittent

I’m not going to go into detail about the specifics on each of these codes. All you really need to know is that if you get one of these codes, it’s probably time to replace your throttle position sensor.

Replacing a Faulty Throttle Position Sensor

Replacing your throttle position sensor can be a very easy job or an intermediate job. It all depends on what kind of car you drive. 

On older cars, the TPS is often a simple plug and play part that’s easy to access on your car. It’s generally just two bolts and a wire connection. You could literally replace it in minutes.

However, on some newer cars, the TPS might be integrated into the throttle body. If this is what your car has, you might have to remove the throttle body and take it apart to access the internal sensor. Or you might even have to replace the entire throttle body unit.

Replacing your throttle position sensor on a newer car can get a little tricky. You may have to remove a couple parts to access the throttle body. And sometimes you’ll have to deal with coolant lines that attach to the throttle body. You’ll have to plug or pinch these lines to prevent coolant from spilling out.

If you know your way around an engine, you should be able to identify where your throttle position sensor is.

But if you’re not comfortable with your mechanical know-how, it might make sense to ask a gearhead friend for help. Or take your car to your local mechanic

Throttle Position Sensor Cost

How much does a throttle position sensor cost? This isn’t an easy question to answer. It all depends on your car. 

If you have an older car and the sensor IS NOT integrated into your throttle body, the part will likely cost in the $20 – $50 range.

If you have a newer car and the sensor IS integrated into the throttle body, the part can cost several hundred dollars.

Resetting the ECU After Replacement

The reason why many people think they need a throttle position sensor reset is because sometimes the car’s ECU needs to be reset.

But have no fear… in most cases, the ECU will automatically detect the new throttle position sensor and will recalibrate on its own.

If you’re one of the “lucky” ones who needs to reset your ECU, don’t panic. All you need to do is connect your car to an OBD tool and clear the error codes.

Don’t have an OBD tool? You can try going to your local big-box auto part story and ask if they can do it for you. Or just have your local mechanic do it.

Disconnecting your battery

The other option some people use to reset their ECU is disconnecting their battery.

I personally don’t love this option. Mostly because I’m lazy and don’t want to reprogram all my preset radio stations. (Give me a break, I’m busy writing articles for this website, lol)

My laziness (and yours, don’t lie) aside, the bigger reason I don’t like disconnecting a car battery is because EVERYTHING on the car needs to re-learn. And sometimes this takes time to do.

I actually ran into a situation where disconnecting my battery caused problems. I had performed some work on my Volvo V70 once and needed to disconnect the battery. The following week, I took my V70 in for its emissions test and it failed! 

The car had no problems, but because I disconnected the battery,  several systems were in the recalibration process, and they couldn’t provide data to the emission testing center. So I had to wait a month and have it re-tested.

Is this a big deal? No. But I had the inconvenience of having to take my car back to the emissions testing station for a second time.

Conclusion

A throttle position sensor reset is not possible because your car’s throttle position sensor is a simple device that doesn’t have advanced computer chips inside of it. If you are having problems with your throttle position sensor, you most likely need to replace the sensor.

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