In a nutshell, a P0122: Throttle Position Sensor Circuit Low Voltage lets you know that the fuel injection computer notices that the throttle position sensor is producing a lower than normal voltage.
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.
Contents of this tutorial:
You can find this tutorial in Spanish here: Código P0122 ¿Qué Significa? (1995-1997 2.7L Honda Accord) (at: autotecnico-online.com).
APPLIES TO: This tutorial, on the P0122 OBD II trouble code, applies to the following vehicles:
- 2.7L V6 Honda Accord: 1995, 1996, 1997.
RELATED TROUBLE CODES:
What Does Trouble Code P0122 Mean?
A P0122: Throttle Position Sensor Circuit Low Voltage lets you know that the throttle position sensor's signal is stuck at a very low voltage when you're stepping on the accelerator pedal and the voltage should be greater.
To better understand why this is a problem, take a look at the section: What Does The Throttle Position Sensor Do?
Common Symptoms Of A P0122 Trouble Code
The throttle position sensor is a mission-critical component of the fuel injection system.
As such, when it fails, your Honda Accord's engine performance will suffer. You'll see one or more of the following symptoms:
- Rough idle.
- Very low idle.
- Very high idle.
- Engine may start and stall.
- 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.
And as you're probably 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.
Now, as the throttle plate opens, the throttle position sensor signal voltage increases. At wide open throttle (WOT), the TPS signal voltage is around 4.5 Volts.
As the throttle plate closes, the throttle position sensor signal voltage decreases.
As long as the fuel injection computer sees the TPS voltage signal increasing/decreasing, it knows you're stepping ON/OFF the accelerator pedal (and that the TPS is functioning correctly).
What Causes A P0122 Trouble Code?
The most common cause of a P0122 trouble code is a bad throttle position sensor.
A bad TPS is not the only cause of a P0122 trouble code, here are a few other things that can cause it:
- An open-circuit problem in the TPS signal wire between the TPS and the fuel injection computer.
- An short-circuit problem in the TPS signal wire between the TPS and the fuel injection computer.
- A bad TPS connector.
- Bad fuel injection computer (although very rare).
How To Diagnose And Repair A P0122 Trouble Code
Troubleshooting and repairing a P0122 trouble code involves testing the throttle position sensor.
The purpose of the throttle position sensor test is to see if it is really stuck producing a single low voltage value as you open/close the throttle plate.
The TPS test also must include making sure that the throttle position sensor is getting 5 Volts and Ground from the fuel injection computer.
If your test results confirm that the TPS signal voltage DOES NOT increase 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.
Testing the throttle position sensor is not hard, you find the test explained in detail 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:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression (1995-1997 2.7L Honda Accord).
- How To Test The Head Gaskets (1995-1997 2.7L Honda Accord).
- P0420 -What Does It Mean? (1996-1997 2.7L Honda Accord).
- How To Test The Ignition System (1995-1997 2.7L Honda Accord).
If this info really saved the day, buy me a beer!