P0123 TPS Code Explained (2002-2007 4.7L V8 Dodge Ram Pickup)

  • By: Abraham Torres-Arredondo
  • Created: 01 July 2025
  • Updated: 01 July 2025
  • Articl Id: 845
P0123 TPS Code Explained (2002, 2003, 2004, 2005, 2006, 2007 4.7L V8 Dodge Ram Pickup)

If your 2002–2007 4.7L V8 Dodge Ram pickup has set a P0123 TPS trouble code, it means the throttle position sensor (TPS) is reporting a voltage that's too high —even when the throttle isn't wide open.

This can cause the PCM to misjudge how far open the throttle really is, leading to poor driveability and even limp mode for the automatic transmission.

Luckily, you don't need a scan tool to figure it out —just a basic multimeter and a few simple checks.

In this tutorial, I'll explain what code P0123 really means, what causes it, and if you should replace the TPS or test it before replacing it.

Contents of this tutorial:

APPLIES TO: This tutorial applies to the following vehicles:

  • 4.7L V8 Dodge Ram 1500 Pickup: 2002, 2003, 2004, 2005, 2006, 2007.

TPS MULTIMETER TESTS:

TPS WIRING DIAGRAMS:

OTHER TPS TROUBLE CODES EXPLAINED:

What Does P0123 Really Mean?

DTC code definition, depending on what your scan tool displays:

  • Generic Definition: P0123 – Throttle/Pedal Position Sensor/Switch A Circuit High Input.
  • Factory Definition: P0123 – Throttle Position Sensor Voltage High.

Code P0123 means the PCM is seeing a TPS (Throttle Position Sensor) voltage that's too high —typically above 4.5 Volts— even though the throttle plate isn't fully open.

On your 2002–2007 4.7L V8 Dodge Ram pickup, the TPS normally produces a voltage signal ranging from about 0.3 Volts at closed throttle to around 4.5 Volts at wide open throttle (WOT).

If the voltage is stuck near the top end of that range, or it suddenly spikes past 4.5 Volts when it shouldn't, the PCM triggers a P0123 TPS voltage high fault.

In other words, the PCM thinks you're flooring the gas pedal —when you're really not. That mismatch is a red flag, and it sets the code because the TPS signal no longer makes sense for the current engine operating condition.

Understanding the code is just the first step —next, we'll cover the real-world symptoms that usually come with a P0123.

Common Symptoms Of Code P0123

When your 2002–2007 4.7L V8 Dodge Ram pickup sets a P0123 TPS voltage high code, the symptoms can show up suddenly or come and go.

Because the PCM thinks the throttle is wide open, it may try to limit power or shift aggressively. Here are the most common symptoms you might notice:

  • Engine stuck in limp mode (reduced power).
  • Hard or delayed transmission shifts.
  • High or erratic idle.
  • Check engine light on (CEL).
  • Poor acceleration or hesitation.

These symptoms are your first clue —but to fix it right, you'll want to understand what actually causes a code P0123. Let's break that down next.

What Causes Code P0123?

As mentioned earlier, code P0123 sets when the PCM sees a throttle position signal that's stuck too high —typically above 4.5 Volts— for the actual throttle opening.

This can be caused by the TPS itself, but not always. Here are the most common reasons this code shows up:

  • Faulty TPS sensor stuck at high output voltage (internal failure).
  • Signal wire shorted to the 5 Volt reference circuit.
  • Signal wire shorted to battery voltage (direct 12V contact).
  • Open in the TPS signal wire (no connection back to the PCM).
  • Open in the Ground circuit shared by the TPS.
  • Intermittent wiring problem —like a loose terminal or damaged insulation.
  • PCM issue (rare, but possible).

To find out what's really going on, you'll need to test the TPS with a multimeter. You can check the signal wire, confirm the 5 Volt supply, and verify Ground —all without removing the sensor. Here's a step-by-step guide to help you do exactly that:

If you're wondering whether it's worth testing or just replacing the sensor outright, that's exactly what we'll look at next.

Should You Replace The TPS?

Most folks (even shops), when they see a P0123 TPS voltage high code on their 2002–2007 4.7L V8 Dodge Ram pickup, automatically replace the sensor and see if that clears the code. And honestly, sometimes that works just fine.

I don't blame them, and there's nothing wrong with that — eight times out of ten, that's gonna solve the code and the TPS issue causing havoc on engine or transmission performance.

Not only that, but the throttle position sensor is one of the easiest sensors to replace because of where it's located (very accessible). You don't have to take a bunch of stuff off to get to it.

I also want to mention that what makes this “just replace it” strategy work is that the TPS doesn’t cost an arm and a leg.

But if the issue lies in the wiring or power supply, a new sensor won’t fix anything. That’s why I recommend testing the TPS before buying a replacement — especially since testing it is so easy and doesn’t require any special tools. You just need a basic multimeter and a few minutes of your time.

Still, if you're leaning toward replacing the TPS and getting your truck back on the road today, here are a couple of parts I recommend. These links point to quality sensors that fit your 2002–2007 4.7L Dodge Ram and are from brands I trust:

And just so you know —buying through one of these links helps support this site and keeps the tutorials coming. It won't cost you anything extra.

But if you'd rather test it first and know for sure, here's the full guide that walks you through how to check the signal wire, 5 Volt supply, and Ground with just a multimeter:

More 4.7L V8 Dodge Ram Pickup Diagnostic Tutorials

I've written quite a few tutorials for the 4.7L V8 Dodge Ram pickup. You can find them in this index:

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

Thank You For Your Donation

If this info saved the day, buy me a beer!

If This Info Saved the Day, Buy Me a Beer!