P0123 -What Does It Mean? (1995-1997 2.7L Honda Accord)

A P0123: Throttle Position Sensor Circuit High Voltage lets you know that the fuel injection computer notices that the throttle position sensor is producing a higher than normal voltage when it should be lower.

In this tutorial I'll explain what this trouble code means. I'll also explain what's involved in troubleshooting it and the tests you can perform to find its cause and solution.

En Español You can find this tutorial in Spanish here: Código P0123 ¿Qué Significa? (1995-1997 2.7L Honda Accord) (at: autotecnico-online.com).

APPLIES TO: This tutorial, on the P0123 OBD II trouble code, applies to the following vehicles:

  1. 2.7L V6 Honda Accord: 1995, 1996, 1997.

RELATED TROUBLE CODES:

  1. P0122 -What Does It Mean? (1995-1997 2.7L Honda Accord).

What Does Trouble Code P0123 Mean?

A P0123: Throttle Position Sensor Circuit High Voltage lets you know that the throttle position sensor's signal is stuck at a high voltage value when it should be lower.

To be a bit more specific: The TPS reports that the throttle plate is open when the fuel injection computer knows that it is not open.

Take a look at the section: What Does The Throttle Position Sensor Do?

Common Symptoms Of A P0123 Trouble Code

The throttle position sensor is a mission-critical component of the engine management system and is constantly monitored by the fuel injection computer as soon as you start your Honda Accord's engine.

As such, when it fails, your Honda Accord's engine performance will suffer. You'll see one or more of the following symptoms:

  1. Check engine light is illuminated.
  2. Rough or low idle.
  3. Very high idle.
  4. Engine may start and stall.
  5. Little to no acceleration

What Does The Throttle Position Sensor Do?

The throttle position sensor's job is to report the changes in the throttle plate's angle as it opens/closes to the fuel injection computer.

As you're already aware, the throttle plate is connected to the accelerator pedal via an accelerator cable. As you step on/off the accelerator pedal, the throttle plate opens/closes.

When the throttle plate is closed (for example, you've got your foot off the accelerator pedal), the signal voltage is about 0.4 to 0.9 Volts DC.

As you step on the accelerator pedal, the throttle plate opens. This causes the throttle position sensor's signal voltage to increase.

At wide open throttle (WOT), the TPS signal voltage is around 4.5 Volts.

As you release pressure on the accelerator pedal the throttle plate closes. This causes the throttle position sensor's signal voltage to decrease.

As long as engine is running and the TPS voltage signal increases/decreases, your Honda Accord's fuel injection computer knows you're stepping on/off the accelerator pedal (and that the TPS is functioning correctly).

What Causes A P0123 Trouble Code?

The most common cause of a P0123 trouble code is a bad throttle position sensor.

A few other things can cause P0123 trouble code to light up your 2.7L Honda Accord's check engine light:

  1. An open-circuit problem in the TPS signal wire between the TPS and the fuel injection computer.
  2. A bad TPS connector.
  3. Bad fuel injection computer (although very rare).

How To Diagnose And Repair A P0123 Trouble Code

Troubleshooting and repairing a P0123 trouble code involves testing the throttle position sensor.

The purpose of the test is to see if the TPS is really stuck producing a single high voltage value as you open/close the throttle plate.

Once the problem is confirmed, the next step is to make sure that the throttle position sensor is receiving 5 Volts and Ground from your 2.7L Honda Accord's fuel injection computer.

If your test results confirm that the TPS signal voltage is stuck at one high voltage value as you open/close the throttle plate and the sensor is getting 5 Volts and Ground, then you can conclude that the sensor is bad and needs to be replaced.

I've written a tutorial that'll help you test the throttle position sensor with a multimeter (no scan tool required), you find it here: How To Test The TPS (1995-1997 2.7L Honda Accord).

Where To Buy The TPS And Save

The following links will help you comparison shop for the throttle position sensor of a known and solid name brand (Dorman):

More 2.7L V6 Honda Accord Tutorials

You can find a complete list of 2.7L V6 Honda Accord tutorials in this index:

  1. Honda 2.7L Index of Articles.

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

  1. How To Test Engine Compression (1995-1997 2.7L Honda Accord).
  2. How To Test The Head Gaskets (1995-1997 2.7L Honda Accord).
  3. P0420 -What Does It Mean? (1996-1997 2.7L Honda Accord).
  4. How To Test The Ignition System (1995-1997 2.7L Honda Accord).
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Honda Vehicles:

  • Accord 2.7L V6
    • 1995,
      1996,
      1997