Error P0123 Code – Definition, Causes and How to Fix it

I’ll be going you all you need to know about the P0123 code that appears on your vehicle’s OBD-II scanner.

The error P0123 is a diagnostic trouble code that’s mostly associated with the malfunctioning of the Throttle Pedal Position Sensor/Switch (TPS) A circuit high input.

This Error code is stored to alert users that the Engine control module has received a signal higher than the usual specification from the pedal position sensor.

There are many reasons why this will likely occur and symptoms to watch out for to enable you to perform proper diagnosis and repair.

What Causes P0123 Code

One or a combination of the following will cause your vehicle to run into error P0123 Code.

The Throttle pedal position sensor circuit A range output to the ECM went above the specified voltage of 4.54 volts for more than 2 seconds.

  1. Faulty Throttle Pedal Position Sensor
  2. The wiring harness between the ECM and the TPS
  3. Carbon or dirt surrounding Throttle Pedal
  4. Loosely fixed TPS

Signs/Symptoms of Error P0123 Code

Your vehicle should show one or more of the below symptoms if it ever runs into a P0123 code.

  • The check engine light will illuminate
  • The ECM enters into fail-safe mode
  • Little or no throttle response
  • Slow movement due to the ECM controlling engine speed
  • Poor Acceleration
  • Lack of Power
  • Poor Mileage
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Also, these symptoms might differ depending on your vehicle manufacturer’s ECM fail-safe pattern. However, expect a slow vehicle movement with minimal throttle response.

Also, the P0123 code might be accompanied by other OBD-II codes which will require you to use the manufacturer-specified test to clear them.

How to Fix the Error P0123 Code

The P0123 code is quite easy to repair, follow any of the below guides to clear the TPS error from your check engine light.

  1. Throttle position sensor wiring replacement or repair
  2. TPS sensor replacement
  3. Check the connections and
  4. Perform a voltage check on the circuits

After implementing one or all of the above-mentioned fixes on your vehicle, the error should be cleared permanently in meantime.

Mistakes to Avoid While Diagnosing the Error P0123 Code?

Here’s a certain mistake we make while trying to diagnose the Error P0123 code on our vehicles.

  1. Not performing a visual inspection of wiring and connections
  2. Failure to scan, document, and clear after testing a particular fix
  3. Inability to cross-check repairs and connections before initiating a test especially when a new Sensor is installed
  4. Performing a TPS replacement without troubleshooting other causes of the P0123 code
  5. Using aftermarket parts that are out of specification.
  6. Not verifying if the TPS sensor A and B circuits cause the error.

If you adhere to the following caution before applying the fixes then the error P0123 code is 90% fixed.

Also, you can call the attention of an auto mechanic for professional services if you can’t handle the issue alone.

How Serious is the P0123 Code

You’ll encounter various driving issues since the ECM puts the vehicle in fail-safe mode until the error code is resolved.

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You will also encounter poor Acceleration, jerking, and limited speed which can make the car experience almost unenjoyable.

It’s best to resolve this code once and for all to ensure your safety and that of other road users.


How to Reset the throttle position sensor

Resetting your throttle position sensor requires you to either disconnect your battery negative terminal for up to 300 sec (5 minutes) or either remove the fuse connecting to your ECM.

Can you drive with a faulty throttle position sensor?

It is dangerous to drive with a faulty TPS since your engine speed is now managed by your ECM. It could also cause greater harm to your car engine if not resolved on time.

Can Throttle Body be Cleaned?

Yes but it’s a service that can be done by auto professionals only with the use of tools and specialized cleaners.


The Error P0123 code isn’t something that you should hesitate in fixing, asides from the poor driving experience; it could leave you stranded and also cause more damage to your engine.

Simply follow the above guide to diagnose and fix the P0123 code.