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P2138: Throttle/Pedal Pos Sensor Voltage Correlation

Are you at your wits end? Have you already crossed your fingers and tried to reset your vehicle's computer? Do you feel that there is no other choice but to ask Google, “how do I fix trouble code P2138?” Well, thankfully, you have landed on our page, an overview guide which will help you not only understand the P2138 error code and why the check engine light is on but also how to potentially resolve the problem.

Understanding Drive by Wire

Before we dive into the error code and its meaning, it is necessary to understand the upgrades to the throttle during the 1990s and how that has impacted automotive design and functionality. Vehicles that existed before the 1990s were relatively simple in design when compared to the computer-driven models of today. For example, the throttle used to be controlled by a direct cable connection between the throttle and the gas pedal. However, the new electronic throttle control systems use internal motors, accelerator sensors and throttle position sensors, which are all linked into the engine management computer, creating a reasonably complex system upgrade over the pre-1990s models.

Learning the Meaning of P2138

What does the code P2138 mean? This is a diagnostic trouble code and is considered a generic powertrain code because it applies to all vehicle makes and models from 1996 on. However, this specific code refers to an issue that is inhibiting the throttles ability to open and close properly. While this code is similar across all make and models, it is possible that it might be referenced in a slightly different way. For example, on an Infiniti, the code might be described as a “throttle position sensor circuit range/performance” error, but in a Hyundai, it might be specified as an “electronic throttle control system malfunction power management.”

Watching for Possible Symptoms and Causes

There are several potential warning signs or symptoms of this error code. The first will likely be the illumination of the check engine light. This alert might be followed by a sudden loss or lack of power at cruise speeds. Also, the car might stall when you come to a complete stop. You might experience no acceleration or even a stuck throttle.

In addition to the numerous symptoms, there are also several potential causes for such an error message. For example, the wiring connections might be loose, corroded or shorting to the ground. Also, it is possible that the throttle body is distorted, causing problems in the rotation of the gears. Another possibility is that any number of sensors failed, or the throttle body itself failed. Additionally, the engine management computer may have failed.

Fixing Potential Problems

A quick word of warning, the throttle control system is incredibly fragile, and it is necessary to handle everything with extreme care. If you do not have full confidence in your abilities, then you might want to take your car to an experienced mechanic. However, if you choose to move forward, then you will want to inspect all the throttle body components, which are located inside the housing. The only element outside of the body is the accelerator pedal sensor. Review all the items, including the cover for signs of wear and distortion. Replace what needs replacing.

The OBD-II scanner error code P2138 problem, while described as a generic code, is not a common issue. Unfortunately, the problems that cause such a code often require the resolve of experienced hands because the electronic throttle system is incredibly vulnerable to damage. Therefore, before attempting any repairs yourself, be sure that you are confident in your abilities.

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