P2128 Code: Throttle/Pedal Position Sensor/Switch “E” Circuit High

The electronic throttle control (ETC) regulates the operation of the throttle valve. It determines when, by how much, and how long the valve should stay open. To achieve accurate performance, the ETC draws data from devices like the throttle position sensor and accelerator pedal position sensor.

The PCM will log a P2128 code when it detects a signal input voltage from the throttle position sensor or pedal position sensor that exceeds the correct values stored in its memory.

What Does the P2128 Code Mean?

The diagnostic trouble code (DTC) P2128 indicates “Throttle/Pedal Position Sensor/Switch “E” Circuit High.” It applies to vehicles with electronic throttle control, a type of drive-by-wire system.

The accelerator pedal position sensor activates when you step on the gas pedal. It transmits a voltage signal to the PCM to inform the latter about how much power the engine needs to produce.

In response, the PCM will open the throttle plate to let more air through. The throttle position sensor measures how far the plate has opened, allowing the PCM to adjust the opening as needed.

The PCM regularly checks the signals sent by the throttle position sensor and pedal position sensor. If the signal from one of these sensors is too high for a certain amount of time, it will set the generic code P2128.

Note: The definition of code P2128 can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of a Code P2128?

• Failed accelerator pedal position sensor
• Bad PCM
• Faulty throttle control motor
• Circuit problems, such as a damaged wire or poor connection
• An issue with the throttle position sensor

What are the Common Symptoms of a Code P2128?

• Illuminated warning lights
• Reduced engine performance
• Engine goes into limp home mode, which will limit its performance

How to Diagnose the P2128 Code

The P2128 code is a generic code that can show up in various makes and models. The specifics can vary between individual cases–an approach that works for some vehicles may not prove suitable for others.

Running diagnostic checks for P2128 and other codes requires confidence, experience, knowledge, and skill in DIY auto repair. There are many times when it’s better to bring your vehicle to a trusted auto repair shop.

To help you get started, here is a video that can give you an idea of what the process might involve:

How to Fix the P2128 Code

Attempting to fix a P2128 code can become a challenging task if you don’t have the right tools and know-how to test the electronic throttle control. In most cases, it’s best to leave the job to professionals.

Are you a DIYer with advanced technical knowledge and hands-on experience to test and replace their vehicle’s electronic throttle control on their own? It’s still advisable to draw upon the related repair manual or refer to an online repair database to refresh your knowledge and make the job easier.