6 Symptoms of a Bad Throttle Position Sensor (and Replacement Cost)

A bad throttle position sensor is the last thing that you will ever wish to have on your ride. The purpose of a throttle position sensor is to keep your car running like it’s supposed to by controlling the throttle.

With the passage of time, the sensor will start to get worn and may eventually have to be replaced. The important question is how to identify any bad throttle position sensor symptoms so that you end up replacing the right sensor?

Honestly speaking, it is not easy to detect throttle position sensor issues. However, there are specific throttle position sensor signs to look for to help ensure you find the culprit.

What Does a Throttle Position Sensor Do?

The primary purpose a throttle position sensor (TPS) is to give information to the car’s computer about the throttle. It senses the air, heat, and light, and sends the information to the ECM which adjusts the throttle and fuel supply accordingly.

All vehicles have something called a “throttle” which controls how much fuel is allowed to flow into the engine. The throttle position sensor is what monitors the throttle position from the shaft.

Basically, this sensor is connected to a computer inside the vehicle which shares information sent by the driver. This information contains the actions of the driver such as accelerating, power steering and so forth.

So anytime you step on the gas pedal to accelerate your vehicle, the computer sends this information to the sensor so that the throttle knows how much fuel to let flow into the engine.

In the old days, there used to be a cable that was connected from the throttle to the accelerator. But now in the technological age, the car’s computer controls when the throttle opens and closes by the feedback it gets about the acceleration of the vehicle.

See Also: Drive By Wire Throttle Working Principle

Top 6 Bad Throttle Position Sensor Symptoms

A faulty throttle position sensor sends incorrect information to the ECM resulting in various issues in the engine, its performance, and fuel economy.

Below are common symptoms of a faulty TPS. In most of the cases, all of these symptoms will show together making it easier to detect the faulty component.

1) Car Jerks

no power steering

Jerking or bucking of the vehicle is the most common symptom of a bad TPS. These jerks can be experienced during hard acceleration or when under moderate load.

What makes diagnosing it tricky is that the bucks and jerks may be completely random and not even occur for some stretches of time. The reason this happens is that the ECM doesn’t get correct information from the TPS as to how much to throttle the car.

2) Idle Surging

engine idle speed

Idle surging can be caused due to other issues in the car, but if it happens in conjunction with other throttle position sensor symptoms, the culprit is often the TPS.

At idle, the ECM will not get the correct information and the throttle will variate randomly causing idle surges.

3) Check Engine Light

check engine light

The check engine light will randomly turn on and off even if the car is running smoothly without any jerks and stalling. This is often the first ever symptom of a bad TPS.

Using a code reader, you should be able to confirm whether a faulty TPS is the culprit or a different component. Diagnostic trouble codes P0120, P0121, P0122, P0123, and P0124 are what will commonly appear.

4) Engine Stalling

car shuts off while driving

The engine can stall for no reason and without any warning. This happens when the TPS gives incorrect information to the ECM. The engine can stall at high speed, at low speed, or even at idle.

5) Acceleration Issues

car hesitates when accelerating - gas pedal

A faulty throttle position sensor will not let your car accelerate normally. Though this doesn’t happen all the time. You may experience slow acceleration, acceleration surge at both high and low speeds, hesitation or delay in acceleration, and other related symptoms.

6) Problems Switching Gears

driving high altitude

The issues with acceleration can lead to gear transmission problems as the ECM doesn’t get the correct information about the acceleration. This leads to incorrect shift points which can cause both early or delayed shifts.

Can You Fix a Bad Throttle Position Sensor?

As soon as you see a mix of these throttle position sensor symptoms, you should test the TPS and if it isn’t functioning properly, it needs to be replaced. Unfortunately, a TPS cannot be repaired as it is a tiny sensor but the good news is that a new sensor “usually” isn’t too expensive so you can get back on the road soon enough.

Throttle Position Sensor Replacement Cost

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TPS replacement cost

If you need to have your throttle position sensor replaced, the cost will depend on the type of car you have. But the average cost of this replacement job isn’t that expensive.

The parts will cost you between $75 and $130 on average. The labor costs will be anywhere between $60 and $90, depending on the hourly rate of the mechanics. So in total, you can expect to pay between $135 and $220 for a throttle position sensor replacement.

Since replacing the TPS is fairly easy in most cases (depending on its location), you may be able to save yourself some time by doing it yourself. A quick search on Youtube is often all it takes.

Going to a dealership is going to cost you more so for most jobs (such as this one), we recommend you find a trustworthy independent mechanic whether by recommendations from family and friends or by reading online reviews.

And, of course, there may be taxes and fees added onto these costs which are determined by your location. But it’s still not too expensive when you consider everything else that could go wrong with your car.

Can You Drive With a Bad TPS?

Now you may be wondering when you’ll need to have your throttle position replaced. The simple answer is when your computer can no longer detect any signal from the throttle position sensor.

The will likely force your computer to stall the engine and only allow it to run at low RPMs, which means the car will only move at slow speeds. This is a safety feature enforced by the computer so that your engine doesn’t get too damaged.

Related: What is Limp Mode?

A throttle position sensor will generally fail simply from the wear and tear of driving the vehicle for many years. There is nothing you can really do to prevent this sensor from failing because it will just happen on its own.

The only thing you should do is have it replaced as soon as you notice these symptoms occurring in your vehicle.

12 thoughts on “6 Symptoms of a Bad Throttle Position Sensor (and Replacement Cost)”

  1. I just replaced my TPS & now all the symptoms are WORSE! Now when I take off it goes from 1st all the way to Overdrive almost immediately & when I floor it it won’t kick down to lower gear? I assume There is an adjustment I need to make. 1997 Infiniti QX4

    Reply
    • I’m not sure if there’s an adjustment required. Check the specifications of the factory service manual to know for sure.

      What was the reason for replacing the TPS? Perhaps it wasn’t the root cause of the issue.

      Reply
  2. I have a mystery I need help. Driving my 97 Oldsmobile cutlass supreme 3100 engine drove perfectly. Goin down the highway all of a sudden it does a lil jerk I loose all power to the accelerator won’t rev up and it dies pull over won’t start next day it fired right up. So I replaced the crank sensor drove perfect for a day then going down the highway same thing died won’t start. Replaced the ignition module drove perfectly for a day then same thing won’t start. I’m lost and out of ideas can anyone please help. The fuel pump is work I have spark the fuel filter brand new. I’m out of ideas. Could it be the coil packs or the throttle position sensor? Goes straight from running fine no loss of power no jerk no nothing to dead.

    Reply
  3. I have a 2004 trailblazer that has rpm surge in drive but runs fine in 3rd I had coil packs go bad so I replaced them. No check engine light and no codes could it be a bad throttle sensor

    Reply

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