Honda Accord P0123 – Test your TPS Sensor

Over time the throttle sensor in your Honda Accord can go bad. When this happens your engine computer won’t know exactly how far you are opening the throttle body, and your Accord check engine light will turn on. Use a OBDII scan tool to analyze the stored Diagnostic Trouble code in your Honda. When you discover that the OBDII MIL check engine light is for a Honda Accord P0123 trouble code, it means there’s a problem with your throttle position sensor. This code is a code for Throttle Position Sensor Circuit High Voltage.

The Honda Accord P0123 trouble code means that the engine computer is seeing a throttle position sensor value that’s too high. When this happens your engine computer cannot properly deliver the right amount of fuel and control spark events. Today I’ll be showing you how to test the Accord Throttle position sensor in a 2001 Honda with a 2.2 liter SOHC engine in it.

What is the Honda Accord TPS Sensor?

The TPS sensor or throttle position sensor in your Honda is a basic potentiometer. It’s mounted to the shaft of your throttle body. When you depress the gas pedal in your Accord, the throttle body will open. This turns or rotates the shaft that’s connected to the TPS and this movement is measured by the throttle sensor. This translates into a voltage signal that your engine computer will understand. Using this data your engine computer can deliver the right amount of fuel so that your Accord engine operates smoothly.

Honda Accord TPS Sensor

Problems caused by Honda Accord P0123 trouble code

  • Accord won’t start
  • Poor engine idle
  • Non responsive throttle
  • Engine revving or increasing speed on it’s own

Troubleshooting your Honda Accord TPS Sensor

Before you begin to test your throttle sensor, you will need to use a multimeter. There are different kinds of multimeters that you can use, but it’s recommended that you pick up an accurate digital multimeter for this test.

Using this device you’re going to be measuring the real time values at each one of your Accord TPS wires. This will allow you to check and see what part of your TPS is broken or if there’s a problem with your engine harness.

Before you begin testing your TPS sensor in your Honda Accord, you will need to access it. In this year range of Honda however it’s rather difficult to reach the MAP sensor, because of it’s positioning near to the firewall.

How To Fix the Honda Accord P0123 trouble code

To reach your Honda Accord throttle sensor, you’ll need to remove most of the intake tract. This is very easy to do and can be done with just a Phillips screwdriver and a 10mm metric socket. To begin open your Accord hood and trace back the intake piping from your 2.2 liter airbox.

Honda Accord P0123 1

There are several intake vacuum lines that need to be moved out of the way before you can remove the intake piping. Gently disconnect these metal lines from the vacuum hoses and push them aside.

Honda Accord P012331

Pull out the metal PCV tube from the intake piping, you can now move onto the Honda Accord MAP sensor or the GRAY plug.

Honda Accord P0123 2

Disconnect the three pin MAP sensor on top of your throttle body. Make sure not to mix up the GRAY Honda plug with the BLUE TPS plug.

Honda Accord P012 4

Now that is done you can undo the worm clamp that connects the intake piping to the throttle body inlet. Undo this screw and you can disconnect and pull off the intake pipe. This should give you the room to disconnect and test the MAP sensor.

Honda Accord P0123 11

Shown above is the blue connector to your Honda Accord MAP Sensor. This is the unit you’ll be testing to fix your Honda Accord P0123 trouble code. Disconnect this unit now and get your multimeter ready.

Honda Accord P0123 5

The first part of this tutorial to fixing your Honda Accord P0123 trouble code is to measure for power and ground at your Honda Accord TPS sensor harness. To do this you need to turn the Accord ignition to the ON position. Now take your digital multimeter and probe at the PIN labeled 1 in the Accord TPS wiring diagram below.

Honda Accord P0123 6

This should be a YELLOW wire with a black stripe through it. This should have a switched power signal at this wire. If you have power  here, great move onto testing for the ground signal. That is PIN 3 or the GREEN wire with a BLACK stripe.

The last wire we’ll be checking is the signal wire. This one happens to be PIN 2 or the middle wire that’s RED. Trace back the red wire and expose it in the engine harness, preferably in a location where you have more room.

Now you’ve got to reconnect the TPS sensor and test the signal coming out of the unit. You can do this by measuring the voltage directly at the middle wire of the TPS sensor you just exposed. With the throttle plate closed this wire should be reading around .8 to 1.0 volts of signal. Now you can manually open your throttle body, or have a friend push down on the gas pedal. Open the throttle fully.

At this position the Accord TPS sensor should read around 4.5 volts of signal. If it does so you are okay and there may be another issue that’s causing your Honda Accord P0123 trouble code. Chances are however that you’ll be reading a value that’s much higher from your throttle sensor. That’s the signal that is confusing your engine computer and causing the Honda Accord P0123 check engine light to be turned on. Have any questions about our guide to fixing your Honda Accord P0123 trouble code? Leave them for me below!

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