8 Symptoms of a Bad Throttle Position Sensor (and Replacement Cost)
Though your car was running just fine the last time you drove it, it’s suddenly acting really strange. The idle may be surging, the car jerking while driving, and it might even stall out at a stop light. Your check engine light is probably on as well.
Without plugging in a code reader, it’s a good guess you’re having some sort of problem with the throttle position sensor. Here we go over how a throttle position sensor (TPS) works, go over the most common symptoms of a bad throttle position sensor, and provide some estimates on its replacement cost.
Common Symptoms of a Bad Throttle Position Sensor
If you have a bad throttle position sensor, then the engine control unit (ECU) will not know the position of the throttle. As a result, the engine control unit will not be able to properly regulate the amount of air that enters the engine so that a successful combustion can be made. This will ultimately impact your driving ability to the point where it is unsafe to stay on the road.
When your TPS is damaged or worn out, you’ll likely notice changes in your car’s behavior right away. While you may not recognize the TPS as the root cause, these symptoms should motivate to investigate further or get a professional diagnosis.
Related: Symptoms of a Bad Throttle Body
#1 – Check Engine Warning Light
The throttle position sensor is a key component of the overall internal combustion process. If this sensor goes bad, your engine will ultimately fail to produce sufficient power to accommodate your acceleration needs.
The engine control unit will detect this problem when it exists and then activate the Check Engine warning light on the dashboard. That way, you will be aware that your engine has some kind of problem that needs to be addressed.
A check engine light is one of the first signs of a faulty throttle position sensor. This is because the TPS monitors the throttle’s position and relays this information to the engine control unit. When the TPS malfunctions, it sends incorrect data (or no data), which in turn causes engine performance issues.
The car’s computer detects this inconsistency and triggers the check engine light to alert the driver of a potential problem requiring attention.
Common diagnostic trouble codes related to the TPS include: P0121, P0122, P0123, P0124, P2101, P2135, and P2138.
#2 – Weak Acceleration
With a faulty throttle position sensor, it may incorrectly signal that less power is required, even when the accelerator pedal is firmly pressed down.
This miscommunication results in reduced fuel injection and ignition timing, leading to sluggish acceleration and overall poor engine performance. Naturally, fuel consumption is also affected (as explained below).
#3 – Engine Rough Idling
When you stop or park your vehicle somewhere, its idle RPM shown on the tachometer in your dash should be somewhere in the vicinity of 600 to 900 RPM. If you notice the engine RPM below or above that range while your vehicle is stopped or parked, then you have a rough idle or fluctuating RPM problem with your engine.
This happens because when the TPS malfunctions, it may transmit inaccurate information about the throttle’s position, particularly at idle. This in turn causes the ECU to miscalculate the required fuel amount, leading to an improper air-fuel ratio.
As a result, the engine may receive too much or too little fuel, causing it to run unevenly or stumble at idle.
#4 – Excess Fuel Consumption
Since the throttle position sensor has a major effect on proper air/fuel mixture for burning, inaccurate readings can cause too much fuel to injected into the combustion chamber. This will cause a rich air/fuel ratio which will result in decreased fuel efficiency.
In addition, other sensors depend on accurate readings from the TPS. When that doesn’t happen, those sensors will often compensate for too little or too much airflow. The end result is usually the need to go fill up on gas more frequently than usual.
#5 – Unexpected Acceleration Changes
A malfunctioning TPS can send erratic signals to the engine control unit, causing unexpected changes in acceleration. This may result in sudden surges of power or drops in speed, even when the driver isn’t changing throttle input. The engine might rev unexpectedly or the car could lose power intermittently.
These unintended acceleration changes are obviously quite concerning as they can make the vehicle difficult to control and even dangerous to drive.
#6 – Transmission Issues
A faulty throttle position sensor can also affect automatic transmission performance. The TPS helps determine when it’s time to shift gears based on throttle position and engine load. When it malfunctions, incorrect signals may be sent, causing the transmission to shift at the wrong times.
You might experience harsh or delayed shifts, unexpected downshifts, or the transmission staying in a lower gear longer than necessary. Not only does this affect driving comfort but can also cause increased wear on transmission components. In some cases, the vehicle may even go into a “limp mode” as a protective measure, severely limiting how your car performs.
#7 – Car Won’t Start
In rare cases, a bad throttle position sensor can prevent your car from starting altogether. The engine control module (ECM) relies on input from the TPS to determine the correct amount of fuel to inject during startup. Without this info, the ECM may not initiate the starting sequence or provide the correct fuel mixture, making it impossible for the engine to turn over.
You might hear the starter motor engage, but the engine won’t catch. This symptom is often accompanied by other symptoms above including an illuminated check engine light.
#8 – Lack of Power When Towing
If you use your vehicle for towing, a faulty throttle position sensor can be particularly problematic. Towing requires precise control of the engine’s power output, which depends heavily on accurate throttle position information.
With a faulty TPS, the engine may not respond correctly to throttle inputs, especially under the increased load of towing. You might notice a major lack of power when trying to accelerate or climb hills while towing. Not only is this frustrating, but it also becomes dangerous when needing to navigate steep inclines or merging onto a highway.
Throttle Position Sensor Replacement Cost
Best places to order parts? See: 19 Best Online Auto Parts Stores
An engine needs the right amount of air just like it needs the right amount of fuel. If the engine does not receive the proper air amount, then its internal combustion process is compromised. This means inadequate power generation and a whole list of other problems.
You won’t be able to postpone this situation for too much longer. You’ll have no choice but to get a diagnostic check done on your vehicle by a certified mechanic.
If it is revealed that your throttle position sensor is bad, then you will need to replace it right away. The average replacement cost for the throttle position sensor is anywhere from $110 to $200. The parts cost is anywhere from $75 to $105 while the labor cost is anywhere from $35 to $95.
In addition, you will have to account for any extra fees and taxes that get added on as well. Overall, you shouldn’t have to spend more than $250 to get this replacement job done. If you shop around for an inexpensive mechanic, you might find a lower hourly rate.
Here’s a new section on Common Misdiagnoses for your article:
Common Misdiagnoses (When It’s Not the TPS to Blame)
Throttle position sensor symptoms are often mistaken for other issues. Recognizing these common misdiagnoses can potentially save you time and money.
- Mass Airflow Sensor (MAF) Failure – The MAF sensor also measures air intake, and its symptoms can be similar to TPS issues. Both can cause poor acceleration and rough idling. However, MAF problems typically don’t cause the sudden acceleration changes associated with TPS failure.
- Vacuum Leaks – A vacuum leak can cause erratic idling and poor performance, similar to TPS issues. However, vacuum leaks often produce a distinct hissing sound that TPS problems don’t.
- Fuel Injector Problems – Clogged or bad fuel injectors can cause symptoms like rough idling and poor acceleration, which might be mistaken for TPS issues. However, fuel injector problems typically don’t cause the check engine light to come on as quickly as TPS issues do.
- Ignition System Issues – Problems with spark plugs, ignition coils, or wires can cause misfires that might feel similar to the jerking associated with TPS failure. However, ignition issues usually produce more consistent symptoms across all driving conditions.
- Catalytic Converter Blockage – A clogged catalytic converter can cause lack of power and poor fuel economy, similar to TPS issues. However, catalytic converter problems typically worsen gradually over time, while TPS issues often appear more suddenly.
How a Throttle Position Sensor Works
Every vehicle with an internal combustion engine has something called a throttle body, also referred to as a butterfly valve. This valve is positioned in the middle of the intake manifold and the air filter.
The job of the throttle is to manage the air flow that goes into the engine. As the driver steps on the gas pedal to accelerate the vehicle, more air is needed in the internal combustion chamber of the engine.
While more air enters the engine, more fuel gets injected into it as well. The ignition of this mixture is how engine power is created.
The position of the throttle determines how much air enters the engine. There is a component in the fuel management system called a throttle position sensor which detects this position.
When you want to accelerate the vehicle, the sensor gives the throttle position information to the engine control unit. From there, the engine control unit will manage the throttle and allow it to take in whatever amount of air is needed in the engine.
The harder you step on the gas pedal, the wider the throttle will open to allow more air flow into the engine. At the same time, more fuel will be injected into the engine cylinders to create a balanced mixture for combustion.
See Also: 3 Causes of an Electronic Throttle Control Light On
Electronic vs Mechanical Throttle Position Sensors
Throttle position sensors come in two main types: mechanical and electronic. The electronic version is often referred to as a “drive-by-wire” system. Here’s how they compare:
| Feature | Mechanical TPS | Electronic TPS |
|---|---|---|
| Connection | Physical cable | Electronic signals |
| Sensor Type | Potentiometer | Hall effect or optical sensor |
| Design | Simpler | More complex |
| Precision | Less precise | More precise |
| Response Time | Slower | Faster |
| Durability | More prone to wear | Generally more durable |
| Maintenance | May require adjustments | Less frequent maintenance |
| Diagnosis | Generally easier | Can be more complex |
| Integration | Limited | Easily integrates with other systems |
| Failure Mode | May allow some manual control | Often has electronic fail-safe modes |
He’s known for his attention to detail and problem-solving skills and enjoys coming up with out-of-the box solutions when the situation requires it.
When he's not troubleshooting customers' cars, you'll most likely find him working on his current project ('96 Bronco) or cooking Italian food for his family.
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My 2008 honda Odyssey will shut off once it good and warm. It will start back after a few minutes but then ut has little to no acceleration
Check the ignition coils. Also, consider doing a compression test to see if you have low compression.
Hi can this cause engine failure?
I think it’s unlikely. Why do you ask?
I have a 2001 Acura Integra ls auto.. It will not rev over 5000 rpm and it would stall usually at low rpms it would crank over but not start, I’m guessing my son was hitting over 5000rpms it feels like the engine is restricted. Also I keep hearing the words limp mode, which is a safety system so the car doesn’t have any further damage to it. After a few it would start up and run like crap. When its cold it starts first time every time. its also intermittent. I was driving it today to the gas station keeping it below 5000 Rpms and I had no issues. I replaced all the usual service parts a few more. Plugs, wires, cap and rotor, fuel filter and pump, main relay. I got a CEL for the cat so I replaced the cat and both o2 sensors, but it still will not rev passed 5000rpm. any ideas? I’ve also replaced the map sensor and cleaned the throttle body. All codes are clear when checking including the one for the cat now.
I’m working on a 1997 Chevy 4.3 vortex new tps,map sensor, electronic module cap,rotor,AC Delco plugs egr.and I brought it up to 1500 rpms and held it there it runs real rough any suggestions? Thanks
I would hook up a scan tool and look at some live data if you can. Check fuel trims to see if it’s running rich or lean. It might be a good idea to check the timing, too.
Well Im having same ish,suddenly my lexus starts drinking fuel like a v12,it doesn’t exceed 60kph and rpm 3000, God help me in about to climb a hill it won’t pick till I floor the pedal and gbam my car engine sound will be making noise like I am on rom 5000. I scanned and it all says throttle position error,out of range bla bla bla,circuit bla bla bla,I already have placed an order on a used throttle body exact factory oem,I can’t wait to get it. But for now ,I’m driving the car like that,just that it’s vibrates,gear acts funny sometimes plus if the ac is on and my 02 sensor bank 1 sensor 2 has cut,my god I buy almost 25litres every 2 days . I can’t cope . Help me.
Can you be more precise with the error codes? That “bla bla bla” sounds like useful information in the right hands, which could help you resolve the issue more quickly.
I love your work and do you guys have app for this site
Thanks for the feedback, glad you enjoyed it! I’m afraid not, we have this website only.
I drive a 2008 Lexus IS 250 and have been experiencing an erratic but mild idling when i engage to drive or reverse. I have a normal fuel consumption and no sudden exhiliration. Please advise.
Could be an issue with the idle air control valve. Do you have a check engine light, or just an erratic idle?
I have Audi Q3 2014 reg 2.0… last couple of days, I’m stepping on the gas pedal it doesn’t rev like normal, it seems to have lost power and the car acceleration is weak and I have to really step on it to get power. It’s not like it doesn’t accelerate, but have to press it harder.
Acceleration on cruise control is just fine, it picks up just fine when notching up the speed in the 5 miles increments it’s just as responsive as it has always been.
It looks like something up with the gas pedal acceleration, I don’t have warning light.
What could it be?
You could try pulling the spark plugs to see if they look like they need to be replaced. Sometimes as plugs age they aren’t able to burn the air fuel mixture as well.
I’m driving a 2006 Audi A3 2.0fsi and the problem I noticed, it idles itself when parked/iddling and the revv count is not normal
Perhaps the idle needs adjusting. It may be a problem with the idle air control valve (IAC), or you may have a vacuum leak. A smoke test will help you test for vacuum leaks.
I’m driving Golf V, its always having a hard start and need your feet to be on the accelerator when you start a car. and it stall out on a stop lights
Perhaps cleaning the MAF sensor or throttle body will help. If it doesn’t, you’ll probably have to do some testing to figure out what the problem is.
Could be the o2 sensor
Can a throttle body sensor be replaced in a 1994 Mercedes Benz S420 without replacing the whole throttle body? And can a MAF sensor be replaced without replacing the whole Unit?
Michael
I have a 2002 buick lesabre and i ran the codes on the car and there is only 1 code popping up at p0172 code. So I’ve been doing my research and this stuff is telling me it could be my throttle position sensor or my mass airflow sensor. So i ordered both parts and too see if this will work for me, but if anyone can tell me what else it could be, because when i start the car up it straight up and dies on me and i replaced fuel pump and fuel filter. But the code keeps coming up as p0172 and saying running too rich from bank 1. So i dont know what else could this problem be but i order these 2 parts and hopefully it will fix my problem. But i would like to get a second suggestion from someone who will know about this.
There are a number of causes for this code. It could also be the oxygen sensor.
Instead of throwing parts at the problem and hoping for the best, it will be a lot cheaper and easier to test any of the sensors in question to ensure they are working properly. Grab a repair manual for your car that has a wiring diagram (Haynes and Chilton manuals should both have this). These diagrams should contain the expected voltage for each pin on the harness, tell you which pins should have continuity on the sensors, etc. Test each sensor with a multimeter to ensure they are working as expected, and you will narrow down the list of possible causes considerably.
I have Nissan extral qr20 sometimes have a high rave counter up to 3 while driving at 30 falin to engage into next gear and sometimes it just performs very we’ll what could be the problems pls
My santr xing when i start my car suddenly race 5 second after ill drive gear change suddenly high hideling after 1km engine its take normal condition
Does Nissan sunny ex saloon 2006 have throttle sensor
I have a 2006 Subaru Outback 2.1 Is the throttle position sensor and the throttle body all one unit?
Hi, thanks for the Info it’s so helpful. My Car Toyota Mark II Grade just have this issue. I will replace the throttle sensor and see how it responds. The engine dashboard light is still on so will see after the replacement.
Yesterday as I was driving my car lost power and the engine stopped. The engine warning didnt appear.I pushed it aside and tried to start the engine once more.Well it had hard start but picked and I continued with the journey. What might have caused that considering its automatic transmission?
Check the fuel pump inside the fuel tank. Maybe it’s starting to fail
Do throttle position sensor cleaner work
I had been having problems with the transmission on my 2004 Explorer Eddie Bauer edition, mostly stalling when I came to a stop and gear slippage. I then noticed problems with cruise control, which led to finding out that there was a problem with the Throttle Position Sensor. Transmission shop said it was loose, bolt needed to be tightened, but there must have been more to it, as they estimated the fix at approx. $200. A few days before a schedule appointment to have the TPS fixed and transmission issues further diagnosed, I got in a bad car accident. I don’t remember much other than shortly after getting in my car to drive, I felt like I had no control over the car and wasn’t able to turn left. I had gotten off the highway after having driven only a few miles. The car came to a t-intersection and went flying off the highway, went airborne, down a hill and then finally stopped. I later found out someone had called 911 and said I had only been going around 35 mph on a 55-65 mph highway. I feel almost certain that the problems with my TPS and/or transmission were the cause of the accident, but can’t prove it because of my limited memory. Looking for help, advice. Thanks.
Wow, very scary situation. Hope that you’re ok. It’s very possible the TPS was at fault and caused unintended acceleration. But I’m definitely not the expert when it comes to how the cause of an accident such as yours is determined. I would suggest seeing if there are any related recalls on your vehicle that may have contributed to what happened.
02 Ford f 150 turns over will crank sometimes but will go dead then it want crank for hour after cools off want accelerate to what I am machine the floor I know it has to be a sensor help me please
Does a Ford ranger have a accelerator pedal position sensor.
I have a polo classic 1.4 1997 model fuel injector. I did an overhaul and full service on the engine. But still the car isn’t starting, any advice?
What all did you do as part of your overhaul and full service?
Does it crank, but won’t start? When diagnosing this situation, remember a car needs four things to run: air, fuel, spark, and compression. If the timing is off on any of these, the vehicle is unlikely to start.
The problem is most commonly fuel or spark. I would start there and verify you are getting both at the correct time.
I have a 1992 Chevy Lumina APV Van with a 3.8 liter motor. I tested the old TPS and it shows as bad. It registers a constant 4.5 volts when I move the spring loaded tab on the TPS. The new one registers between .5 volts to a steady increase of 4.5 volts as it should when I move the tab. My idle is still super high. My question is does the little spring loaded bar on the TPS need to hook into something like the accelerator cable bracket maybe? Or, does the tab just need to rest against the bottom of the accelerator bracket/spring?
In the heat of the day all of sudden I can’t get acceleration the check engine light do not come on .in the early morning no problems 2006 Chev Cobalt LS 2.2