What Is the P2138 Code?
Symptoms
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Seriousness
Can I Still Drive?
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Difficulty of Inspecting
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The P2138 is defined as “Throttle/Pedal Position Sensor/Switch “D”/”E” Voltage Correlation.” It is triggered when the vehicle’s Engine Control Module (ECM) detects that the signals from the two throttle position sensors or the two accelerator pedal position sensors don’t correlate. When this occurs, the ECM cannot identify the actual accelerator position and will illuminate a warning light and limit your vehicle’s throttle response to under half throttle.
In modern vehicles, the new electronic throttle control technology consists of an accelerator pedal position sensor and an electronically controlled throttle body that pairs with an internal motor. Two embedded throttle position sensors also accompany this to infer correlation, and the ECM monitors the entire process. When the accelerator pedal is depressed, a sensor sends the desired throttle opening to the ECM. In response, the computer sends a voltage reading to the electric motor to open the throttle plate. Next, the two throttle position sensors embedded in the throttle body convert the amount of throttle opening to a voltage signal sent to the computer. Finally, the computer monitors the correlation of both of these voltage readings. When the voltages agree, the system is operating as it should. However, when they deviate for two or more seconds, the ECM triggers the P2138 code to indicate a malfunction somewhere in the system.
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What Are the Symptoms of a P2138 Code?
The first symptom you may notice with the P2138 code is a sudden loss of power at cruising speeds. Next, your vehicle may experience trouble with acceleration and loss of power, and unresponsiveness from the engine. The Check Engine Light will also illuminate when the code is set to indicate an issue exists. Finally, you may find that the throttle sticks at any RPM, and you cannot change the position.
What Are Some Causes of a P2138 Code?
One of the first causes of the P2138 code is a defective ECM. Circuit problems, such as spoiled or corroded wires or faulty connections, can also cause the issue. You will often find that a defective throttle position sensor can cause the code to set. A damaged throttle body will also lead to the ECM setting of the P2138 code and damaged wiring or sensors of the accelerator pedal. These are leading causes of the issue because they inhibit the ECM from gathering and correlating the voltages to keep the vehicle operating as it should. Finally, the ECM may need a software update if it’s not working normally, or you may need to replace the ECM altogether in rarer cases.
How Serious Is the P2138 Code?
The P2138 code is severe as it directly affects your ability to control your vehicle’s acceleration. For example, if the code causes your vehicle’s throttle to stick, this can lead to extremely hazardous conditions on the road and even accidents. With that said, you should address this issue as soon as you run into it.
Can I Still Drive with a P2138 Code?
As we mentioned, qualified technicians do not recommend driving with the P2138 code as it can impair your ability to control your car’s acceleration. This can be very dangerous on the road and even lead to potential accidents and damage to your vehicle and others. This is why you should immediately take your car to a certified service station when confronted with the P2138 code.
How Easy Is It to Diagnose a P2138 Code?
The first step in diagnosing the P2138 code issue is visually inspecting the throttle body and the throttle body motor and throttle position sensor. A qualified technician will then examine the system for any circuitry issues related to the wiring and the connectors. They will then test the throttle body motor and the throttle position sensor to ensure they are correctly functioning by following the manufacturer’s recommended process. Finally, the technician will test the ECM to ensure it is working correctly.
How Difficult Is It to Inspect a P2138 Code?
Since the inspection process of repairing any P2138 issue takes several steps and involves complicated systems like the throttle body assembly and throttle position sensors, a qualified technician with experience working on these issues should be the one to do it. With that said, it’s not recommended to DIY this issue yourself at home as you may end up causing further damage to your engine.
With that said, a technician will begin by replacing the throttle body motor or the throttle body assembly if it’s defective or damaged. They may also repair or replace any wiring associated with the throttle body motor. Replacing the throttle position sensor may also be a part of this process and replacing the wiring that leads to the throttle position sensor. Finally, a technician may opt to replace the ECM if it’s defective and unable to perform properly.
Need Additional Help with Your P2138 Code?
By following the steps laid out in this guide, you should spot the signs of a P2138 issue and take the correct steps to prevent further damage to your engine. In addition, it’s essential to have your vehicle inspected by certified technicians to repair any issues with your car so that you can keep your vehicle running longer.
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