P2138 Error Code:Throttle/Pedal Position Sensor Voltage Correlation - august 6
Diagnostic codes usually point to a malfunction in a specific location of your car system, and the P2138 error code is one of the many error codes your car can generate. This code signifies a throttle or pedal position sensor voltage correlation, and this part is generally located in your car’s powertrain.
This article will help you break down this malfunction tarting from understanding the throttle or position sensor to understanding what how different voltages affect this part. You will learn about the causes of this code, the usual symptoms associated with it, and how to diagnose and eliminate the code.
What is the P2138 Error Code?
The throttle and pedal position sensor which is connected to the throttle body is also called the accelerator pedal position sensor. When you push on the gas pedal of your car, the throttle valves open up to take in air, this action notifies the sensor of how far you want to accelerate and the sensor sends this information to the electronic control module (ECM) as how far you want to accelerate.
The ECM uses this information to adjust the air intake from the intake system to produce the amount of power from the engine required to make this acceleration level possible. The throttle position sensor is crucial for the air-fuel mixture to aid acceleration.
The P2138 error code is generated when the signals sent from the gas pedal and the throttle position sensor do not match.
Causes of the P2138 Error Code
It’s not one malfunction that triggers this code in your car, however, different malfunctions occur at different components that can trigger this code. Usually, this code is triggered by a malfunction related to the throttle system.
Faulty throttle position sensor
The throttle position sensor is responsible for monitoring how much your foot presses on the gas pedal. It sends this information to the ECM to adjust the combustion process to accommodate acceleration. When this sensor is faulty, it sends inaccurate information to the ECM and this can affect combustion and in turn trigger this code.
Faulty accelerator pedal position sensor
The accelerator pedal position sensor measures the amount of air that rushes in after you push on the gas pedal, and it also sends this information to the ECM along with that from the throttle position sensor to aid combustion. When this sensor is faulty, it sends inaccurate information to the ECM which can affect combustion and trigger this error code.
Damaged sensor wiring
If the wiring on the throttle or accelerator position sensor gets damaged or disconnected from its appropriate position, the P2138 error code will be triggered to notify your car of this problem.
Sensor circuit malfunction
The circuits connect the throttle and accelerator pedal position sensor to the ECM, and when they are damaged or have a fault, correlated signals will be sent to the ECM and it will affect the engine’s combustion process.
Faulty throttle body actuator
The throttle body actuator controls the opening and closing of the throttle valves to permit the intake of air. When the throttle body actuator becomes faulty, the valves open and close incorrectly which affects the engine’s combustion process.
In modern cars, this component is also called an electronic throttle control (ETC) and performs the same function as the throttle body actuator.
Faulty ECM
When the ECM is faulty, it receives signals from the throttle and accelerator pedal position sensor and misinterpretes these signals which greatly affects combustion processes and causes the P2138 error code to be triggered.
Symptoms of P2138 error code
When this code is generated by your car system, you will observe some unusual behaviors from your car.
Check engine light comes up
The check engine light is a warning light that tells you that there is a malfunction somewhere in your car. This light is an oil jar illuminated by an amber or orange light, you can find this light on your car’s dashboard display.
Poor acceleration
With throttle parts like the sensors and body actuators malfunctioning, your car will experience poor acceleration when you push your foot on the gas pedal. This poor acceleration can be noticed by unresponsiveness or sluggishness when attempting to accelerate.
Engine stall
Engine stalls occur when your engine temporarily stops working this condition usually feels like a jerking motion and it is characterized by a loud low-pitched sound made by your car.
Reduced throttle response
The throttle doesn’t respond as quickly to any force from the accelerator pedal and the engine in turn also does not react quickly or with the same force when the throttle sensor sends an input.
This can lead to a temporary loss of power sometimes.
Hesitation under acceleration
When it feels like your car is misfiring when you attempt to accelerate, then your car is hesitating under acceleration. This is one of the most common symptoms of the P2138 error code.
Limited driving modes
Your car may deactivate certain driving modes to maintain safety while driving. This means that your car’s speed and acceleration will be limited to prevent your engine from severe damage.
Troubleshooting P2138 Error Code
Before attempting to carry out any repair procedure on your car, you need to confirm if this code is present because for some people, observing the symptoms alone isn’t sufficient to tell if this code is present.
To confirm the presence of this code in your car, you need to use an on-board diagnostic (OBD) scanner. This scanner works by directly displaying the error code(s) present in your car once it’s connected.
You should note that these repairs should be made only if the cause of this error code is confirmed, and if you aren’t sure about doing the repairs on your own, you can contact a mechanic. After using an OBD scanner to confirm this code, here are some possible repairs you can make to eliminate this code
Repair or replace the throttle/pedal position sensor
If a throttle/pedal position sensor is the cause of the P2138 error code, then you can identify the fault and fix it. However, if this component is damaged beyond repair, you will need to get a replacement. A replacement of this part is between $50 to $300, and this cost depends on the make and model of your car.
Repair or replace faulty wiring
If the wring on the throttle/pedal position sensor has been removed, then you can put it back in place to clear this code. However, if the wiring has been damaged, you’ll need to make a replacement and the cost of this replacement varies.
Throttle body repair or replacement
If any damage has been done to the throttle body, then it means your car will have difficulties opening and closing or closing the throttle valves. A mechanic can give this part a repair if the situation calls for it or a replacement will be needed. Replacing the throttle body should cost between $200 to $800, and like every other repair, this amount depends on the make and model of your car.
Conclusion
When the P2138 error code is triggered in your car, it means that there is a malfunction with your car’s throttle/pedal position sensor. These sensors together are responsible for sending signals to the ECM about the air-fuel mixture required for acceleration, which is why when there is a fault, you may notice poor acceleration, engine stalls, reduced throttle response, and hesitation.
After reading this article, you should have learned how to diagnose and confirm this code as well as the possible repairs you can make to eliminate it.
