What Does The Throttle Position Sensor Do? (3.4L V6 Chevrolet, Pontiac)

The throttle position sensor (TPS) is an important engine management system component and as such, when it fails, engine performance will suffer.

In this article, I'll answer some of the most commonly asked questions about the throttle position sensor.

I've also included the link to the TPS test tutorial that will help you test it with a multimeter.

You can find this tutorial in Spanish here: El Sensor TPS ¿Qué Es Y Para Qué Sirve? (1996-2005 3.4L V6 Chevrolet, Pontiac) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 3.4L V6 Chevrolet Impala: 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Chevrolet Monte Carlo: 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Chevrolet Lumina Minivan: 1996.
• 3.4L V6 Chevrolet Venture: 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.

• 3.4L V6 Pontiac Aztek: 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Grand Am: 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Montana: 1999, 2000, 2001, 2002, 2003, 2004, 2005.
• 3.4L V6 Pontiac Trans Sport: 1996, 1997, 1998.

What Does The Throttle Position Sensor (TPS) Do?

The fuel injection computer needs to know the throttle plate angle as you step on or step off the accelerator pedal. The component that is tasked with this particular job, is the throttle position sensor (TPS).

The throttle position sensor is designed to produce an increasing voltage signal as the throttle plate opens.

Once the throttle plate starts to close, the TPS voltage signal decreases back to its base voltage (usually around 0.5 to 0.9 Volts DC).

What Happens When The Throttle Position Sensor (TPS) Goes Bad?

When the throttle position sensor fails, it'll usually stop creating a voltage signal that corresponds to the throttle plate angle.

To be a bit more specific, no matter how much the throttle plate opens (or closes), the TPS voltage signal stays stuck in one value.

Without the correct throttle plate angle information being sent to the fuel injection computer, engine performance and driveability will suffer.

In the next section, you'll find a list of common symptoms you'll see when the TPS fails.

What Problems Can A Throttle Position Sensor (TPS) Cause?

When the throttle position sensor fails, you're going to see one or more of the following symptoms:

• Check engine light illuminated in the instrument cluster.
• TPS trouble codes registered in the fuel injection computer's memory:
  • Code P0121: Throttle Position Sensor Performance Problem.
  • Code P0122: Throttle Position Sensor Signal Voltage Low.
  • Code P0123: Throttle Position Sensor Signal Voltage High.
  • Code P1121: Throttle Position Sensor Intermittent High Voltage.
  • Code P1122: Throttle Position Sensor Intermittent Low Voltage.
• Engine hesitates when you step on the accelerator pedal.
• Lack of power when accelerating the vehicle.
• Bad gas mileage.
• Engine idle either too high or too low.
• Rough engine idle.
• The engine may start and immediately stall.
• The engine cranks but does not start.

How Can You Tell If The Throttle Position Sensor (TPS) Is Bad?

It's not possible to correctly conclude that the TPS is bad based on just symptoms and trouble codes alone.

The only way to be 100% sure that the TPS is bad is to test it.

In the next section, I'll go into some of the specifics of the TPS test.

How Can I Find Out If The Throttle Position Sensor (TPS) Is Bad?

The only way to find out if the throttle position sensor is bad, without replacing it, is to test it.

The throttle position sensor can be tested with a simple multimeter.

The test procedure is as follows:

1. Check for TPS trouble code stored in the fuel injection computer's memory.
2. Make sure that the TPS is getting power.
3. Make sure that the TPS is getting Ground.
4. Make sure that the TPS signal increases/decreases as the throttle plate is opened/closed.

If the TPS has failed, its output voltage signal will not increase/decrease as you open/close the throttle plate.

You can find the throttle position sensor test explained in a step-by-step manner here: How To Test The Throttle Position Sensor (3.4L V6 Chevrolet, Pontiac).

Can I Drive My Car With A Bad Throttle Position Sensor (TPS)?

In most cases, the engine performance problems caused by a bad TPS will not allow you to safely drive the vehicle.

But, even if the vehicle can be driven, you should avoid doing so.

Where Can I Buy The Throttle Position Sensor (TPS)?

The following links will help you to comparison shop for the throttle position sensor (of known professional automotive brands- NO knockoffs) for your 3.4L V6 Chevrolet (Pontiac).

NOTE: All of the 3.4L V6 equipped Chevrolet and Pontiac vehicles covered by this tutorial use the exact same throttle position sensor.

More 3.4L V6 Chevrolet, Pontiac Tutorials

You can find a complete list of 3.4L V6 Chevrolet (Pontiac) tutorials in this index:

• GM 3.4L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test Engine Compression Test (3.4L V6 Chevrolet, Pontiac).
• How To Test A Blown Head Gasket (3.4L V6 Chevrolet, Pontiac).
• What Does The CKP Sensor Do? (3.4L V6 Chevrolet, Pontiac).
• What Do The Spark Plugs Do? (3.4L V6 Chevrolet, Pontiac).