How to Fix Error Code P2138: A Step-by-Step Guide

Error code P2138 is a generic trouble code indicating an issue with the throttle/pedal position sensor/switch D/E voltage correlation. This code may be caused by a faulty or deteriorating throttle body or by a faulty or deteriorating accelerator pedal assembly. The most common cause of this code is a loose or failing connection between the throttle body and the accelerator pedal assembly.

To fix this error code, first inspect the wiring and connectors between the throttle body and the accelerator pedal assembly and ensure that they are properly secured. If any of the connections are loose, tighten them and recheck for codes. If any of the connections appear corroded, replace them with new ones. Once that is done, clear all codes from the system and test drive your vehicle to confirm that it has been fixed.

How Do I Fix Error Code P2138?


Automobiles are complex machines with many different parts and components that work together to provide a smooth and reliable ride. Unfortunately, due to wear and tear, age, or improper maintenance, these parts can sometimes malfunction. One of the most common issues is an error code P2138. This code indicates an issue with the throttle position sensor, a device that monitors the position of the gas pedal and sends signals to the engine control module. Understanding what this code is, how to diagnose it, repair it, and prevent it from happening again is essential for keeping your car running smoothly.

Identifying Error Code P2138



Error code P2138 is a generic trouble code which indicates an issue with the throttle position sensor in the vehicle. This sensor monitors the position of the gas pedal and communicates this information to the engine control module. If there is an issue with this sensor, it can cause reduced acceleration performance, difficulty starting up the engine, or even trigger a check engine light.

Diagnosing Error Code P2138



The first step in diagnosing any problem is to identify what could be causing it. For error code P2138, there are several potential causes including a faulty or worn out throttle position sensor itself, wiring issues such as corrosion or loose connectors, or a defective electronic control unit (ECU). A diagnostic scan tool can be used to help identify which component(s) may be failing in order for further testing to be done for confirmation.

Repairing Error Code P2138



Once you have identified what could be causing error code P2138 in your vehicle, you can then move on to repairing it. Depending on what component(s) are at fault will determine how they should be fixed or replaced. In some cases this may simply mean replacing a worn out part such as the throttle position sensor itself; in others it might require cleaning or replacing corroded wiring connections; and in some cases it may even involve replacing or reprogramming an ECU. Once all repairs have been completed it’s important to test them for confirmation before moving on with other diagnostics or repairs that might be necessary.

Preventing Error Code P2138



The best way to avoid having any issues with error code P2138 in your vehicle is through regular maintenance and inspection of all components related to this system including wiring connections and sensors. Additionally avoiding overloading components with extra loads such as trailers can help prevent damage from occurring over time as well as monitoring performance of these components regularly so any issues can be identified early before they become major problems down the road.

Common Symptoms of Error Code P2138



The most common symptom associated with error code P2138 is reduced acceleration performance due to an incorrect signal being sent from either one or multiple components related to this system such as a worn out throttle position sensor itself or loose wiring connections etc… Other symptoms include difficulty starting up the engine and/or triggering a check engine light when connected directly into a diagnostic scanner for further troubleshooting information

Common Causes of Error Code P2138



Error Code P2138 can be caused by a faulty Throttle Position Sensor (TPS) or its associated wiring harness, or a malfunctioning Throttle Body Unit. The Throttle Position Sensor is an electronic device that measures the amount of air entering the engine, which helps the car’s computer to control the fuel to air ratio for optimal engine performance. Thus, if the TPS is not functioning properly, it can cause Error Code P2138 to be displayed on the dashboard.

How to Clean a Throttle Body Unit



Cleaning a Throttle Body Unit requires proper preparation and using the appropriate cleaners and tools. Before starting any cleaning procedure, it is important to disconnect the battery terminals and make sure that all other electrical connections are disconnected from the unit as well. Then, using a damp cloth and an appropriate cleaner, such as carburetor cleaner or brake cleaner, clean all surfaces of the throttle body unit including its linkage and throttle plate. Once finished with cleaning, dry off all surfaces with a clean cloth before reattaching all connections.

Tools and Materials Needed to Repair Error Code P2138



In order to repair Error Code P2138, one will need several tools and materials such as a throttle body unit, socket set, screwdrivers and other necessary components depending on your vehicle model. It is also advisable to have access to an automotive service manual detailing specifications for your specific vehicle make and model in order to safely complete repairs without causing further damage.

How to Replace a Throttle Position Sensor (TPS)



Replacing a Throttle Position Sensor starts by locating it on your vehicle. Once located, you will need to remove its old TPS from its mounting bracket before installing a new one in its place. After attaching the new TPS securely in place with screws provided with your new purchase, you should then test it for proper operation by powering up your car’s engine and verifying that no error codes are displayed on your dashboard. If everything checks out okay then you are ready for use!

FAQ & Answers


Q: What is Error Code P2138?
A: Error Code P2138 is an OBD-II generic code which indicates an issue with the throttle/pedal position sensor/switch “B” voltage correlation. This code is associated with the accelerator pedal position sensor and its related components.

Q: What are the common symptoms of Error Code P2138?
A: The common symptoms of Error Code P2138 are reduced acceleration performance, check engine light coming on, and difficulty in starting engine.

Q: What are the common causes of Error Code P2138?
A: The common causes of Error Code P2138 are faulty throttle position sensor (TPS) or wiring harness, and throttle body unit malfunction.

Q: How do I clean a throttle body unit?
A: To clean a throttle body unit, you will need to prepare for the cleaning procedure, use the appropriate cleaners and tools, and follow any manufacturer instructions before proceeding with the cleaning process.

Q: What tools and materials do I need to repair error code p2138?
A: To repair error code p2138 you will need a Throttle Body Unit, Socket Set, Screwdrivers, as well as any additional parts recommended by the vehicle’s manufacturer.

In conclusion, the error code P2138 is a common problem for many vehicle owners. The most common cause for this error code is a faulty throttle pedal position sensor, so it is important to check and replace this part as soon as possible to prevent further damage. Additionally, it is important to make sure all other related parts are in good condition and functioning properly, such as the throttle body and the wiring harness. Finally, it is also recommended to regularly inspect the car’s system and components to ensure that they are all in working order.

Author Profile

Carl Frisch
Carl Frisch
With more than 30 years in the bicycle industry, I have a strong background in bicycle retailing, sales, marketing and customer service. I have a passion for cycling and a dedication to excellence. As a manager, I worked diligently to increase my capabilities and responsibilities, managing up to eleven mechanics (at Palo Alto Bicycles) and later as a working partner in my own store.

As the shop owner of Spoke n’ Word Cycles in Socorro, NM, the success of the mission was my responsibility, which I pursued passionately since we opened in 2003 through the spring of 2011. I am adept at managing owned and loan inventory, preparing weekly & annual inventory statements, and managing staff. The role as managing partner also allowed me tremendous freedom. I used this personal freedom to become more deeply involved in my own advancement as a mechanic, to spearhead local trail building, and advocating for cycling both locally and regionally.

As a mechanic, I have several years doing neutral support, experience as a team mechanic, and experience supporting local rides, races, club events. I consistently strive to ensure that bicycles function flawlessly by foreseeing issues and working with the riders, soigners, coaches and other mechanics. Even with decades of experience as a shop mechanic and team mechanic, and continue to pursue greater involvement in this sport as a US Pro Mechanic, and UCI Pro Mechanic.

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