We help you find the TPS sensor and take a look at the 5 symptoms of a bad throttle position sensor (and how to test it and fix it)
Is your car not accelerating like it used to? Is it idling kind of rough at stoplights? Is your check engine light on? There are some signs that your TPS (Throttle Position Sensor) sensor may need to be cleaned or replaced.
By Maurice Rodriguez
November 1, 2021
But do you know where your TPS sensor is located? Have you ever tested a TPS sensor before? How do you know if it needs to be replaced? If it does need to be replaced how much is that going to cost? Can you do it yourself?
These are the questions that you may be considering if your car is giving you grief. We will answer all these questions and help you understand the replacement cost of a TPS sensor, where to find it, how to clean it, and even replace it in one afternoon.
Table of Contents
What is a throttle position sensor?
A throttle position sensor or TPS sensor is merely a small black plastic sensor attached to the throttle body that calculates the position of the throttle as it opens a butterfly valve to regulate the air intake from the input of the driver. Then this information is passed on to the car’s computer (the electronic control module or ECM) to calculate the air to fuel mixture.
Calculating the air to fuel mixture is important because the car’s engine requires different ratios of air to fuel depending on what the engine is being asked to do, like idle or accelerate. Adjusting these ratios improves fuel economy, acceleration, and emissions. This is why a bad TPS will cause all sorts of issues when it is not operating correctly.
Where is the throttle position sensor located?
We put together a helpful guide on how to locate the TPS sensor on most engines. The actual TPS sensor might look different than our example but you can look up your specific part on any auto parts website and then using this guide you can locate the sensor by starting at your air filter and moving your way to the air intake boot to the throttle body. The TPS sensor will be attached to the throttle body.
To troubleshoot your TPS sensor continue reading for a step-by-step guide.
Symptoms of a bad TPS (throttle position sensor)
We have outlined 5 symptoms to check out to determine if your TPS sensor needs attention. While these are good indicators there may be other symptoms not listed that could still be a faulty TPS sensor. The only way to know for sure is to check the electrical resistance of your TPS sensor is operating correctly. Keep reading to know exactly how to check your TPS sensor for malfunctions.
But to get a general idea if you are on the right track check out these 5 signs below.
How do I test my TPS sensor?
The process of testing your TPS sensor is not hard but does require attention to detail as you can damage your wires or your Multi-Meter if not done properly. Also, this method only works on mechanical throttle bodies. To easiest way to know if your vehicle has a mechanical throttle body is to turn the engine on, have someone else rev the engine while in park, and look under the hood and see if a cable is moving a part that looks like the picture below.
There are two sets of instructions, one for those that have access to their TPS wiring diagram and those that do not have access to a wiring diagram.
Material List
- Safety Glasses
- Work Gloves
- Back Probe Kit
- Multi-Meter
- Optional DIY Choice- Paper Clip
With A Wiring Diagram:
This is the preferred method as it will take the guesswork out of determining the outputs of your TPS sensor, potential damage to your wiring harness, and you will know the default reference output signal at idle and the WOT (Wide Open Throttle) voltage specification.
Directions
Step 1. Grab your electrical wiring diagram. On your diagram find the idle reference output (Usually .5 to 1 volts) and the maximum output (WOT) usually 5 volts. But your wiring diagram should be able to tell you the exact figures.
Step 2. Turn the key to the ON position but DO NOT TURN THE CAR ON. The engine should not be running at this point. This is so the Electronic Control Module (ECM) will send current to the TPS sensor.
Step 3. Turn on your Multi-Meter and set it to ready 20V DC current
Step 3. Now we will back probe the TPS sensor by inserting pins from a back probe kit or paper clips if you have them handy. The terminals we want are the ground and the output signal to the ECU. Make sure your pins DO NOT touch as this will not give you a good testing signal.
Step 4. Once the pins are in, attach alligator clips to the pins and to your testing leads. Make sure you connect the ground to the right lead and the return signal to the positive lead.
Step 5. If your vehicle produces a current at idle, you may see a voltage displayed like .5 volts or 1 volt. Again check your manufacturer for your specific make and model’s TPS specs.
Step 6. Next, we will test the TPS sensor once attached to the multi-meter by gently moving the throttle plate back and forth while watching the multi-meter for jumps or drops in voltage.
Step 7. If you found no issue with the initial idle measurement for your specific vehicle and no issues at wide-open throttle your TPS sensor should be working correctly.
Step 8. But, as the video suggests a real-time waveform from an oscilloscope will tell you if there are any dropouts that you will not be able to see using a multi-meter.
Without a Wiring Diagram:
Material List
- Safety Glasses
- Work Gloves
- Back Probe Kit
- Multi-Meter
- Optional DIY Choice- Paper Clip
This method will work if you do not have a diagram but you will still need to know the initial idle reference signal and the WOT max output signal to know if your TPS is within the proper operating range specified by the manufacturer.
Directions
Step 1. Turn the key to the ON position but DO NOT TURN THE CAR ON. The engine should not be running at this point. This is so the Electronic Control Module (ECM) will send current to the TPS sensor.
Step 2. Locate your TPS sensor and remove the wire harness
Step 3. Turn on your Multi-Meter and set it to ready 20V DC current
Step 4. Ground Black test lead
Step 5. Probe each terminal on the wire harness for the 5V constant supply terminal. This may vary on your vehicle. Consult your specific make and model.
Step 6. Make note of the color wire on the back of the wire harness.
Step 7. Now we will test each of the remainder of the terminals to determine the ground terminal. By process of elimination, the other terminal should be our output signal to the ECM.
Step 8. Switch your multimeter to the Ohm setting with Tone. Like the image below.
Step 9. DO NOT TOUCH THE FIRST TERMINAL (THE CONSTANT 5V) AS IT MAY DAMAGE THE WIRE. Touch the reminder of the two terminals with your positive lead until you hear a tone. Make note of the color wire on the back of the wire harness.
Step 10. Now that we have identified all the wire terminals and their function we can proceed to test the TPS sensor and its voltage.
Step 11. Plug the wire harness back into the TPS sensor and set your multi-meter to 20V DC again.
Step 12. We will back probe the TPS sensor by inserting pins from a back probe kit or paper clips if you have them handy. The terminals we want are the ground and the signal wire. Not the first 5V constant supply terminal that you found in the first step.
Step 13. Once the pins are in, attach alligator clips to the pins and to your testing leads. Make sure you connect the ground to the right lead and the return signal to the positive lead.
Step 14. If your vehicle produces a current at idle, you may see a voltage displayed like .5 volts or 1 volt. Again check your manufacturer for your specific make and model’s TPS specs.
Step 15. Next, we will test the TPS sensor once attached to the multi-meter by gently moving the throttle plate back and forth while watching the multi-meter for jumps or drops in voltage.
Step 16. If you found no issue with the initial idle measurement for your specific vehicle and no issues at wide-open throttle your TPS sensor should be working correctly. But further diagnostic measures may be necessary that a professional may need to diagnose.
Throttle Position Sensor Replacement Cost – Chart
Taking the average of all the parts listed below from suppliers that had TPS sensors available for the models listed we found that the average cost of TPS sensors is $52.50 in 2021. This makes replacing this part relatively inexpensive. The tools needed to diagnose and replace on average should not exceed $110. This includes the TPS sensor for $50, a multi-meter for $40 (if you don’t already own one), and a probing kit for $20 or paperclips if you don’t want to spend the extra money.
| Make/Model | AutoZone | Advanced Auto Parts | Rock Auto | O’Reilly | Amazon |
|---|---|---|---|---|---|
| 2005 Ford Expedition | $84.99 Buy Now | $79.99 Buy Now | $32-$55 Buy Now | $84.99 Buy Now | N/A |
| 2007 GMC Yukon/ Chevrolet Suburban | $52.99 Buy Now | $37-$67 Buy Now | $25-$38 Buy Now | $51.99 Buy Now | $33 Buy Now |
| 2001 Dodge Ram 2500 | $49.99 Buy Now | $38 Buy Now | $20 Buy Now | $38 Buy Now | $50 Buy Now |
| 2004 Toyota Tacoma | $72.99 Buy Now | $72-$130 Buy Now | $30-$38 Buy Now | $73 Buy Now | $65 Buy Now |
| 1998 Jeep Cherokee (XJ) | $29 Buy Now | $65-$105 Buy Now | $14-$33 Buy Now | $55-$62 Buy Now | $28 Buy Now |
How to Replace a TPS sensor?
Material List
Step 1. Disconnect – Remove the negative terminal on your battery before you begin disconnecting your TPS sensor. This prevents any damage to new parts as you reconnect them or unintentional shocks to you.
Step 2. Locate TPS sensor – located near your throttle body. At this point, you should know where to find the TPS sensor. But, if you are still struggling take a look at our quick guide located above.
Step 3. Remove TPS sensor – Unplug the wiring harness from the existing TPS sensor. Remove the mounting screws and keep them in case you don’t get a new set from the new TPS sensor. Dispose of the old TPS sensor.
Step 4. Install new TPS sensor – The new TPS should easily mount and screw right in.
Step 5. Plugin wiring harness – Place the wiring harness onto the new TPS sensor.
Step 6. Reconnect – Put the ground terminal back on your battery.
Conclusion
We hope you have found invaluable information here to guide you on your TPS journey. The TPS sensor is not difficult to diagnose or replace. The skill is in diagnosing your issue and tracking down the source of the problem.
We are all things cars.
Maurice is an avid car enthusiast, foodie, and loves hard rock. When he isn’t writing blogs he enjoys traveling and sight seeing.