07 Common Duramax Throttle Position Sensor Problems

Throttle position sensor or TPS is a very small but one of the most critical parts of a vehicle.

Air and fuel burn in the combustion chamber of an engine.

TPS controls the airflow ratio of the combustion chamber.

Sometimes TPS goes bad and fails to function properly.

There are some signs of Duramax throttle position sensor problems, including hesitation to accelerate, accelerate itself, lack of power during acceleration, poor fuel efficiency, abnormal engine vibration, jerking, check engine light pops up on the dashboard, etc.

This article will discuss 07 Signs of a bad throttle position sensor.

Duramax Throttle Position Sensor Problems [07 Problems with Solutions]

The throttle position sensor controls how much air will go into the engine’s manifold.

More air flows into the engine when the throttle is open, and air flows less when it is nearly closed.

TPS provides airflow information to the engine control module (ECM).

So, the ECM can control the fuel and air mixture entering the combustion chamber by maintaining the throttle position.

When the throttle position sensor goes bad, it causes several problems, including-

  • Acceleration issue
  • Fuel efficiency
  • Check engine warning light
  • Throttle valve misleading
  • Flat signal from the sensor
  • Unstable engine idling/ Shakes while idling

These are the most common signs of a Duramax TPS problem.

Let’s discuss them elaborately.

01. Acceleration Issue

Acceleration Issue

A faulty TPS can affect the acceleration or pickup in your vehicle.

The throttle body regulates the air-fuel mixture entering the engine.

Damaged TPS causes your car to accelerate unevenly, sometimes fast, sometimes slow.

Usually, the valve gets gummed up and restricts the airflow.

There will be 3 different issues with your vehicle’s acceleration if the throttle position sensor has any issues.

  • Lack of Power During Acceleration

You will notice a lack of power than before while accelerating your vehicle.

It will take longer to accelerate than usual and the will be reduced engine power.

  • Accelerates Itself

Sometimes the vehicle will accelerate itself more rapidly than usual if you just put your leg on the accelerator.

It’s a very common sign of faulty TPS.

  • Hesitant to Accelerate

If your vehicle hesitates when you accelerate at a low speed, be sure the throttle position sensor has gone bad.

Lean air to fuel mixture causes hesitation during acceleration.

This problem shows up when the engine fails to maintain the air-fuel mixture ratio.

During accelerating, you might feel the car acting restricted.

02. Fuel Efficiency

Fuel Efficiency

When the throttle body gets damaged, the air-fuel ratio gets messed up.

The problem can cause an altered fuel economy as the combustion gets affected by the strange air-fuel ratio.

Sometimes the fuel economy increases, but the power to the engine decreases as the fuel injection rates get lowered with altered air fuel ratios.

If you think refuelling less frequently is good, you are wrong because it affects your engine in the long run.

The average lifespan of your engine will be interrupted, and there will be major engine problems.

Your engine won’t last 150k miles if the TPS is faulty.

03. Check Engine Warning Light

duramax throttle position sensor problems

Modern throttle body system has air flow meters and position sensors

 that continuously monitor the airflow in particular valve positions.

If the computer detects a change in airflow at a particular valve position, the driver is alerted with a check engine light on the dashboard.

When the Check Engine warning light is illuminated, it is crucial to discover the problem before it worsens. 

04. Miscalculated Position of Throttle Valve

When the TPS sensors fail, the position of the throttle valve is miscalculated, and the ECM alters the fuel injection rates given by the faulty position sensor.

The problem affects the air-fuel ratio, and the engine runs rough at idle.

The engine is the most sensitive at idle, and a slight change in air-fuel ratio affects the engine very badly.

05. Flat Signal from the Sensor

When the TPS is faulty, the computer may read a flat signal from the sensor.

A flat signal from the sensor means that the throttle body is not receiving any input from the sensor.

As soon as you put your foot on the accelerator, the throttle body opens up, but the fuel injection rates will disturb the air-fuel ratio, and the engine stalls immediately.

The problem could be due to several reasons, but bad sensor problems and problems with the throttle body are the main culprits.

06. Unstable Engine Idling

Unstable Engine Idling

The engine is sensitive at idle.

A lot of soot and dirt on the throttle body flap will cause less air to enter the engine and therefore cause a low idle RPM.

Usually, a throttle body cleaning and a throttle body calibration with a diagnostic tool will solve this problem.

Similarly, the gummed-up throttle the initial movement when you first try to move your vehicle from a stop.

Mostly your car shuts down with strange vibrations of the engine.

07. Improper Gear Shifting

An automatic transmission system needs to know the position of the throttle. The throttle opens and closes according to the reading of the ECU.

A faulty throttle position sensor sends misinformation to the ECU and causes gear shifting or transmission problems.

Symptoms of Bad TPS Sensor

Bad throttle position sensors will show some symptoms. You should look for the symptoms given below for a bad TP sensor:

  • Unexpected vibration and noise from the engine
  • Sudden power surges and stalls
  • Hesitation accelerating at low speed
  • Unusual speed changes in high speeds
  • Check engine light flashing without any reason
  • Difficulty in shifting gears
  • Steering abnormalities and difficulty
  • Sudden low fuel economy

Contact the dealership or a nearby mechanic shop to diagnose the issue if you face any symptoms. TP sensor is an important part of the engine and it can lead to a catastrophic situation and damage the engine. So, you should solve the problem as soon as possible.

TPS Sensor Diagnosis

Diagnosis of the TPS needs to be done after you face any symptoms. You can use an OBD-II sensor to diagnose the issue. Here are some error codes and their meaning:

  • P0120: Low voltage input or output from the sensor
  • P0121: TPS circuit switch malfunction
  • P0122: Circuit performance issue in the TPS
  • P0123: High voltage output from the sensor
  • P0124: Intermittent TPS circuit issue

You should try to reset the sensor and if it fails replace the sensor. TPS doesn’t cost that much and it is easy to replace. Take help from a professional if necessary.

Can I Drive with a Bad Throttle Position Sensor in My Duramax?

Yes, you can, but you shouldn’t.

It will cause major damage to the engine.

The lifespan of Duramax is around 400k miles on average.

Many major parts of the engine will be damaged, and it will cost you a lot of money and time to fix them.

The lifespan of your engine will be greatly affected also.

So, driving with a bad throttle position sensor is not advisable.

You don’t need to tow your vehicle. 

Drive slowly and find the nearest mechanical shop.

Taking the vehicle to a mechanical shop and changing the TPS is the best you can do.

02 Solutions for Throttle Position Sensor Problems

No need to worry if you notice signs of bad throttle position sensor in your vehicle.

There are 2 solutions to this problem.

  • Re-installing the TPS

Find out and remove the throttle position sensor from your vehicle and clean it with compressed air.

Then re-install the TPS.

If the problem occurs due to filth in the TPS,

hopefully, it will be solved.

If not, replace the TPS with a new one.

Re-Installing Process of a Throttle Position Sensor

You can remove and re-install the TPS in 8 simple steps.

Step 1: Disconnect the negative battery wires

Step 2: Find out the throttle position sensors

Step 3: Now disconnect the TPS sensor electrical connector

Step 4: Pull out the TPS sensor retaining screws

Step 5: Now remove the TPS sensor

Step 6: Clean the TPS by using compressed air or blowing it into the connector

Step 7: Re-install the TPS sensor and tighten the retaining screws to 90 inches lbs. approximately (10 nm)

Step 8: Connect the TPS sensor electrical wires

When resetting/re-installing fails, replacing the throttle position sensor is highly recommended.

  • Replacing the TPS

If re-installing the TPS after cleaning doesn’t solve the problem, you have only one option.

You must change the TPS.

You can’t fix the throttle position sensor causes it can’t be fixed.

So, don’t try to fix the TPS. 

You will only waste your time if you try.

Instead, replace the TPS with a new one.

08 Steps- How to Replace a Throttle Position Sensor [DIY Method]

You can easily replace the throttle position sensor by following 8 simple steps.

Step 1

Some tools are needed for the replacement process of TSP, including a 10mm socket, flat head screwdriver, and new throttle position sensor.

So, it would be best if you collected them first.

Use work gloves and safety glasses for your safety.

Step 2

Disconnect the negative battery cables to avoid the risk of electrical shock or any error code on your ECM.

Remove the throttle position sensor electrical connectors.

Step 3

After removing electrical connectors, unscrew the clips to remove the throttle position sensor.

Before shopping for a new TPS sensor, read the owner’s manual thoroughly to avoid buying other TPS.

Step 4

Now install the new throttle position sensor.

Step 5

Connect the throttle position sensor connectors.

Step 6

Install the air intake duct.

Step 7

Connect the negative battery cables.

Double-check your work.

Step 8

Start your vehicle and check it in idle and acceleration.

If you have trouble replacing the TPS, we advise you to get it done by a mechanic.

Price of a Duramax Throttle Position Sensor

Don’t worry. 

The throttle position sensor won’t cost much.

The price of the Duramax TPS sensor will be around $50 to $100.

With the mechanical labor cost, TPS will cost anywhere from $100 to $220.

You can change TPS by yourself. 

It’s not very difficult.

Or, you can hire a mechanic to get the job done.

Common Questions on TSP Problems

What Problems Can a Bad Throttle Position Sensor Cause?

There are 07 most common signs of bad throttle position sensor.

  • Acceleration issues like hesitant to accelerate, accelerate itself, lack of acceleration power
  • Check engine warning light pops up on the dashboard
  • Fuel efficiency is low or high than standard
  • Throttle valve of the engine misleads
  • Gear shifting/Transmission problem
  • Engine idling/jerking
  • Computer may read a flat signal from the sensor

We have elaborately discussed these 07 symptoms of a failing throttle position sensor above in this article. Have a look for details.

What happens when you unplug throttle position sensor?

TPS controls the air and fuel ratio for combustion in an engine. If you unplug the sensor, there will be no way to control the air-fuel ratio. As a matter of fact, ECM will stall the vehicle and turn on the check engine light. Sometimes the vehicle loses performance and gets into limp mode. Driving without the sensor may lead to a catastrophic situation and damage the engine.

Can throttle sensor be repaired?

Replacing the TP sensor is the best strategy as it is not very costly. However, it can be reset and repaired for some minor issues. Some minor issues can be fixed with reprogramming. TPS also needs to be reprogrammed after the new sensor installment.

Can a Throttle Position Sensor Problem Change Every Time?

No. It doesn’t change every time. But one problem can lead to another if not solved timely.

You will notice these common problems mentioned above every time.

Will a Bad Throttle Position Sensor Cause Transmission Problems?

Yes. When it fails, it causes gear shifting or transmission shifting problems.

Final Words

Duramax throttle position sensor problems can be solved very easily after diagnosis.

If the check engine light pops up or your vehicle shows any signs of these 07, especially acceleration issues, then you should diagnose your vehicle.

You will know if there is any issue with the TPS.

Just replace the TPS, and you are good to drive your loved vehicle as usual.

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