You are looking forward to a weekend day trip and your car suddenly starts jerking like a bad roller coaster. This is a sure sign you could have a bad throttle position sensor.
Your car may show many bad TPS sensor symptoms or may have a few subtle clues but some of the obvious are sudden stalls, jerking movement, a lack of acceleration, and rough idling. The faster you get the problem diagnosed and the TPS sensor replaced, the more you can control possible damage to your engine.
What Does the TPS Sensor Do?
A TPS sensor is an important part of the throttle body because it monitors the butterfly in the throttle bottle and messages the control panel when the butterfly is open, closed, and how much it’s opened.
To understand the importance of controlling air intake, you must understand the basic concept of combustion that powers cars. You need three things for combustion that gives cars the power they need to move: air, fuel, and fire.
All of that is important because the car sends a certain amount of fuel to the engine depending on the air intake. When you press the gas pedal, it opens the butterfly, and more gas heads to the engine.
This provides more horsepower and allows you to accelerate.
A bad TPS sensor can’t give information regarding the opening and closing of the butterfly, so the whole system is thrown off and you’re left with low acceleration and stalls.
The 7 TPS Sensor Symptoms
Seven symptoms will tell you that you could have a bad TPS sensor. Your car, truck, or van may not experience all seven but will likely experience a couple as the problem worsens.
1. Check Engine Light
This is usually the first sign something is wrong with the TPS sensor. It could also be a sign of something else, even something simple, like a desperate need for an oil change.
The check engine light is an annoying occurrence and most people, unfortunately, don’t pay a lot of attention to it. They think it doesn’t mean too much. It can mean something important so don’t ignore it.
2. Rough Idle
Rough idling is something car owners quickly notice. It feels uncomfortable and your vehicle is making some unusual noises. These are things most drivers can’t ignore. While rough idling could be related to bad fuel or trash in the gas tank, it can also be a sign of a fault TPS signal.
Your vehicle may also stall while idling. That is a clear sign you need to have the TPS sensor checked.
3. Weak or Bad Acceleration
This is another symptom that could be related to several things from bad fuel, to a faulty fuel pump, to trash in the fuel line, to a bad accelerator to a TPS sensor going bad.
Whether it’s the sensor or something else, it is highly dangerous to have trouble accelerating. That makes merging and passing dangerous and it could cause an accident if your car suddenly stops accelerating while in traffic. Get it checked immediately.
Another related problem with acceleration is your vehicle may suddenly accelerate or decelerate on its own. This is definitely a problem with a bad TPS sensor.
This type of behavior happens because the TPS isn’t sending good information about airflow to the controls. So your car computer attempts to compensate for the messages it does receive and that leads to automatically accelerating and decelerating.
This symptom is one of the most dangerous ones as it could cause an accident.
4. Bad Gas Mileage
Despite rising gas prices, you notice you are filling up more than typical. Bad gas mileage, like many of these symptoms, can be related to many things including a bad TPS sensor. It could also be dirty fuel injectors or your spark plugs may need replacing. You won’t know the exact cause until someone looks at your car.
The TPS sensor does, in a way, regular fuel economy because it signals how much airflow is going into the car. That, in turn, regulates how much gas gets dumped into the engine.
A bad sensor could lead to your controls getting the message the airflow is too high and tons of fuel gets poured into the car. That is a waste. A good mechanic costs some money but you’ll save money in the long run by replacing the TPS sensor.
5. Problems With Switching Gears
Whether you’re driving an automatic or stick shift car, it’s important that your car properly shifts gears. A faulty TPS sensor will give your shifting some problems.
This is especially true of automatics because car computers look for your vehicle to be at certain RPMs for it to shift into the next gear. A bad TPS sensor will keep your car at lower or higher RPMs, making shifting a bit clunky.
A problem with shifting can be a safety concern and could also be a transmission issue. It’s best to get it checked out right away.
6. The Car Barely Moves
Cars today have a safety feature called “limp mode.” Your car will automatically go into this mode when it senses there are engine problems. This is a slow, low-performance mode designed to prevent damage to the engine.
If your vehicle is barely moving at any given point in time but everything operates fine, it is in limp mode. It’s time to get it checked out as this could mean other issues besides the TPS sensor.
This is one of the more obvious signs of a faulty TPS sensor. The jerkiness happens because the control module isn’t getting proper information about the air intake so it doesn’t know exactly how much fuel to send. It then sends inconsistent amounts.
With the messaging being all over the map, your vehicle tries to accelerate and decelerate on its own and that is what causes the jerking.
What Should You Do?
A bad TPS should be replaced right away. There is no repairing a faulty sensor and a bad one must be replaced.
You or your mechanic can test the voltage of the sensor with a multimeter. The voltage is typically 1/2 to 1 1/2 volts and 5 volts with the butterfly completely open.
There is no real option of leaving it alone for an extended time. An unattended TPS sensor can cause your motor and transmission mounts to go under extreme stress where they will need to be replaced and that is a far more expensive repair than a TPS sensor.
What Is the Cost of Replacing a TPS Sensor?
Every mechanic will have their own labor and parts cost, depending on where they get the part from but, generally, you can get the TPS sensor replaced for under $200.
Most TPS sensors cost between $75 and $100 and it doesn’t take that long to replace one. It is a fairly simple task for those who know what they are doing.
It can get expensive and complicated if the throttle is hard to access. Some throttles are in open areas, making it a simple and easy fix. Others are in more hidden areas and that requires more of the mechanic’s time.
In that case, you could be looking at a $1,000 repair. Be sure to discuss all of these with your mechanic before you take your car so you know how to plan for an expense rather than get sticker shock.
Can I Replace the TPS Sensor?
You can replace the TPS sensor if you have some basic mechanical skills, some tools like a screwdriver and gloves, and can follow instructions from a tutorial.
It involves disconnecting wires from the sensor, taking out the fault TPS, and installing a new one. The biggest challenge for more people is finding the throttle, and then locating the sensor, in their car.
Most TPS sensors are located on top of the throttle body but look for wires coming out of the housing to indicate where the sensor is located.
You can find the throttle by following the fuel line to the engine. It will lead to the throttle.
Be sure to disconnect the battery before you start any work and wear gloves to protect your hands.
The TPS sensor is a small part but has a big effect on your vehicle. It is something to pay attention to and get replaced as quickly as possible to avoid major repairs down the road.