Car Throttle Position Sensor (TPS): What You Need to Know

A car throttle position sensor (TPS) is a device that monitors the position of the throttle valve in the engine. The throttle valve controls the amount of air that enters the engine, which affects the power and fuel efficiency of the car. The TPS sends a signal to the engine control unit (ECU) or module (ECM), which adjusts the fuel injection, ignition timing, and other parameters accordingly.

The TPS is usually located on the throttle body, which is between the air cleaner and the intake manifold of the engine. It has a butterfly valve that opens and closes as you press and release the gas pedal. The TPS can be a potentiometer, which is a variable resistor that changes its resistance depending on the angle of the throttle valve. Alternatively, it can be a non-contact type sensor that uses magnetic fields or other technologies to measure the throttle position.

The TPS is an important part of the electronic throttle control system, which ensures optimal performance and emissions of the car. It helps the ECU or ECM to maintain the correct air-fuel ratio for combustion and to prevent engine stalling, surging, or hesitation. It also communicates with other sensors, such as the mass air flow sensor (MAF), which detects the amount of air entering the engine.

However, like any other sensor, the TPS can malfunction over time due to wear and tear, dirt, moisture, corrosion, or wiring issues. A faulty TPS can cause various problems for your car, such as poor acceleration, rough idling, reduced fuel economy, or even engine failure. Therefore, it is important to recognize the symptoms of a bad TPS and replace it as soon as possible.

6 Symptoms of a Bad Throttle Position Sensor

Here are some common signs that your car’s TPS is not working properly:

• Check engine light: The most obvious symptom of a bad TPS is the illumination of the check engine light on your dashboard. The ECU or ECM will detect an abnormal signal from the TPS and store a trouble code in its memory. You can use an OBD2 scanner to read the code and identify the problem. Some common codes related to a faulty TPS are P0120, P0121, P0122, P0123, and P0124.
• Poor acceleration: A bad TPS can cause your car to accelerate slowly or sluggishly when you press the gas pedal. This is because the ECU or ECM will not receive accurate information about the throttle position and will not adjust the fuel injection accordingly. You may also experience jerking or surging when you change gears or speed.
• Rough idling: A bad TPS can also affect your car’s idle speed and quality. The ECU or ECM will not be able to maintain a stable air-fuel mixture for combustion and will cause your engine to run too rich or too lean. This can result in rough idling, stalling, or misfiring.
• Reduced fuel economy: A bad TPS can make your car consume more fuel than normal. This is because the ECU or ECM will not be able to optimize the fuel injection for different driving conditions and will inject more fuel than necessary. You may notice a decrease in your gas mileage or an increase in your emissions.
• Engine performance issues: A bad TPS can also cause other problems for your engine’s performance and operation. For example, it can affect your car’s transmission shifting, spark plug firing, exhaust gas recirculation (EGR) system, and cruise control system. You may notice poor drivability, loss of power, hesitation, or backfiring.
• No start condition: In some cases, a bad TPS can prevent your car from starting at all. This is because the ECU or ECM will not receive any signal from the TPS and will not know how much fuel to inject for starting. You may hear your engine cranking but not firing up.

How to Replace a Throttle Position Sensor

If you suspect that your car’s TPS is faulty, you should replace it as soon as possible to avoid further damage to your engine or other components. Replacing a TPS is not a very difficult task, but it requires some basic tools and skills. You can also take your car to a professional mechanic for diagnosis and repair.

Here are the general steps to replace a TPS:

1. Locate the TPS on the throttle body of your engine. You may need to remove some hoses, wires, or covers to access it.
2. Disconnect the electrical connector from the TPS. You may need to press a tab or clip to release it.
3. Remove the screws or bolts that secure the TPS to the throttle body. You may need a screwdriver, a wrench, or a socket and ratchet for this.
4. Lift the TPS off the throttle body and discard it. Be careful not to damage the throttle shaft or valve.
5. Install the new TPS on the throttle body and align it with the throttle shaft or valve. You may need to rotate it slightly to fit it properly.
6. Secure the new TPS with the screws or bolts that you removed earlier. Do not overtighten them.
7. Reconnect the electrical connector to the new TPS. Make sure it clicks into place.
8. Reinstall any hoses, wires, or covers that you removed earlier.
9. Start your engine and check if the check engine light is off and if your car runs smoothly. You may need to clear the trouble codes with an OBD2 scanner or drive your car for a few cycles for the light to go off.

How Much Does a Throttle Position Sensor Replacement Cost?

The cost of replacing a throttle position sensor depends on several factors, such as the make and model of your car, the type and quality of the sensor, and the labor charges of the mechanic. On average, you can expect to pay between $100 and $300 for a TPS replacement, including parts and labor.

The parts alone can cost between $50 and $150, depending on the brand and availability of the sensor. The labor cost can vary from $50 to $150, depending on the complexity of the job and the hourly rate of the mechanic.

You can save some money by replacing the TPS yourself if you have the tools and skills. However, you should always consult your car’s manual or a reliable online guide for specific instructions and precautions. You should also buy a high-quality sensor that matches your car’s specifications and requirements.

Conclusion

A car throttle position sensor (TPS) is an essential device that monitors the position of the throttle valve in your engine. It helps the ECU or ECM to adjust the fuel injection, ignition timing, and other parameters for optimal performance and emissions. A faulty TPS can cause various problems for your car, such as poor acceleration, rough idling, reduced fuel economy, or even engine failure. Therefore, you should be aware of the symptoms of a bad TPS and replace it as soon as possible.

If you need help with replacing your car’s TPS or any other sensor, you can contact RepairSmith for professional and convenient service. RepairSmith brings the shop to you and offers high-quality parts and workmanship at competitive prices. Get a free instant quote today!