The P2138 code is a common issue found in vehicles with electronic throttle control systems. This code indicates a problem with the correlation between the throttle pedal position sensor and the throttle position sensor. When this code is triggered, the engine control module (ECM) or powertrain control module (PCM) detects that the signals from the two sensors do not correlate.
Need tools for your project? Toolbox, a tool rental marketplace, might be worth a look.
The symptoms of a P2138 code can vary depending on the severity of the issue. Some common symptoms include reduced engine power, hesitation or stumbling during acceleration, and an illuminated check engine light. If left unaddressed, this issue can lead to further damage to the vehicle’s engine or transmission.
Understanding the root cause of a P2138 code can be challenging, but diagnosing the issue is the first step towards resolving it. In this article, we will discuss the common causes of a P2138 code, how to diagnose the issue, and the steps you can take to repair or replace any faulty components. We will also provide tips for preventing this issue from occurring in the future and driving with a P2138 code.
Key Takeaways
- The P2138 code indicates a problem with the correlation between the throttle pedal position sensor and the throttle position sensor in vehicles with electronic throttle control systems.
- Symptoms of a P2138 code include reduced engine power, hesitation or stumbling during acceleration, and an illuminated check engine light.
- Diagnosing and repairing a P2138 code requires identifying the root cause of the issue, and may involve repairing or replacing faulty components, as well as preventative maintenance to avoid future occurrences.
Understanding P2138 Code
Definition and Meaning
P2138 code is a diagnostic trouble code (DTC) that indicates a problem with the throttle/pedal position sensor/switch D/E voltage correlation. This code is a generic powertrain code that can affect any make or model of vehicle that has a “drive by wire” throttle system.
Causes of P2138 Code
There are several possible causes for a P2138 code. The most common cause is a failed throttle position (TP) or accelerator pedal position (APP) sensor. Other possible causes include circuit issues and problems with the powertrain control module (PCM).
Symptoms of a P2138 Code
When a P2138 code is present, the driver may experience a variety of symptoms, including:
- Reduced engine power
- Engine stalling
- Rough idling
- Poor acceleration
- Check engine light on
It is important to note that not all of these symptoms may be present at the same time. Additionally, some vehicles may experience different symptoms altogether.
If a P2138 code is detected, it is important to have the issue diagnosed and repaired as soon as possible to prevent further damage to the vehicle.
Diagnosing the P2138 Code
When a driver encounters the P2138 code, it means that there is a problem with the correlation between the throttle pedal position sensor and the throttle position sensor. The driver may notice that the vehicle is not accelerating as it should or is experiencing a loss of power.
Initial Steps
The first step in diagnosing the P2138 code is to visually inspect the wiring harness and connectors for any damage or loose connections. If everything appears to be in good condition, the next step is to use an OBD-II scanner to read the diagnostic trouble code.
Using an OBD-II Scanner
Using an OBD-II scanner is a quick and easy way to diagnose the P2138 code. The scanner will read the diagnostic trouble code and provide a description of the problem. It will also provide live data readings for the throttle pedal position sensor and the throttle position sensor. This information can be used to determine if the sensors are functioning properly.
Manual Inspection
If the wiring harness and connectors are in good condition and the OBD-II scanner does not provide any useful information, a manual inspection of the sensors may be required. This can be done using a multimeter to check the voltage and resistance of the sensors.
In conclusion, diagnosing the P2138 code requires a combination of visual inspections, the use of an OBD-II scanner, and manual inspections. By following these steps, a mechanic can determine the cause of the problem and make the necessary repairs to get the vehicle back on the road.
Electronic Throttle Control Systems
Electronic Throttle Control (ETC) systems are becoming increasingly common in modern vehicles. ETC systems replace the traditional mechanical link between the accelerator pedal and the throttle body with an electronic signal. The system consists of several components that work together to control the throttle body’s position.
Components
The ETC system consists of the following components:
- Throttle Body: The throttle body is responsible for regulating the amount of air that enters the engine. In an ETC system, the throttle body is controlled by an electric motor.
- Accelerator Pedal Position Sensor: The accelerator pedal position sensor (APPS) is used to determine how much the driver is pressing on the accelerator pedal. The APPS sends a signal to the Electronic Control Module (ECM), which then sends a signal to the throttle body.
- Throttle Position Sensors: The throttle position sensors (TPS) are used to determine the position of the throttle body. There are typically two TPS sensors in an ETC system, one on the throttle body and one on the accelerator pedal.
- Electronic Control Module: The Electronic Control Module (ECM) is the brain of the ETC system. The ECM receives signals from the APPS and TPS sensors and sends signals to the throttle body.
Operation
When the driver presses on the accelerator pedal, the APPS sends a signal to the ECM. The ECM then sends a signal to the throttle body, telling it how much to open. The TPS sensors on the throttle body and accelerator pedal send signals back to the ECM, allowing it to monitor the position of the throttle body.
If there is a problem with the correlation between the APPS and TPS sensors, the ECM will detect it and may set a diagnostic trouble code such as P2138. This code indicates that there is a problem with the correlation between the throttle pedal position sensor and the throttle position sensor. It is most commonly found in vehicles with ETC systems.
In conclusion, Electronic Throttle Control (ETC) systems are becoming increasingly common in modern vehicles. The system consists of several components that work together to control the throttle body’s position. If there is a problem with the correlation between the APPS and TPS sensors, the ECM will detect it and may set a diagnostic trouble code such as P2138.
Troubleshooting Common Problems
When a P2138 code appears, it is important to identify and fix the underlying issue as soon as possible. Here are some common problems that may trigger this code and how to troubleshoot them:
Electrical Issues
One of the most common causes of a P2138 code is an electrical problem. This can be due to a wiring issue or a corroded connector. The first step in troubleshooting this problem is to check the wiring and connector for any signs of damage or corrosion. If any issues are found, the affected wiring or connector should be repaired or replaced.
Sensor and Connector Problems
Another common cause of a P2138 code is a faulty throttle position sensor or accelerator pedal position sensor. These sensors are responsible for sending signals to the engine control module, which then adjusts the throttle accordingly. If these sensors are not functioning properly, it can cause the P2138 code to appear. To troubleshoot this problem, the sensors and their connectors should be inspected for any signs of damage or wear. If any issues are found, the affected sensor or connector should be replaced.
Throttle Body and Motor Issues
In some cases, a P2138 code may be caused by a problem with the throttle body or motor. This can be due to a faulty motor or a problem with the throttle body itself. To troubleshoot this problem, the throttle body and motor should be inspected for any signs of wear or damage. If any issues are found, the affected part should be repaired or replaced.
Overall, a P2138 code can be caused by a variety of issues, including electrical problems, sensor and connector problems, and throttle body and motor issues. To identify and fix the underlying issue, it is important to inspect and troubleshoot each of these components carefully. Possible causes of the P2138 code should be identified and addressed as soon as possible to avoid any further damage to the vehicle.
Repair and Replacement
When to Repair
If the P2138 code is caused by a faulty wiring connector or a corroded throttle body wiring, then it may be possible to repair the issue. In this case, the wiring connector should be inspected for any signs of damage or corrosion. If the wiring appears to be in good condition, then applying dielectric grease to the connector may help to prevent future corrosion.
When to Replace
If the P2138 code is caused by a faulty throttle pedal position sensor or throttle position sensor, then it may be necessary to replace the sensor. A faulty sensor can cause a variety of issues, including reduced engine power, stalling, and poor acceleration. If the sensor is found to be faulty, then it should be replaced as soon as possible to prevent further damage to the vehicle.
Cost Considerations
The cost of repairing or replacing the throttle pedal position sensor can vary depending on the make and model of the vehicle, as well as the severity of the issue. In general, the cost of repairing the wiring connector or applying dielectric grease is relatively low, while the cost of replacing the throttle pedal position sensor can be more expensive.
It is recommended to take the vehicle to a trusted mechanic or dealership to diagnose and repair the issue. They can provide a more accurate estimate of the cost of repair or replacement.
Prevention and Maintenance
Preventing a P2138 code from appearing is possible by taking some preventive measures. Regular maintenance of the vehicle is the first step in preventing this issue. The throttle pedal position sensor and the throttle position sensor should be checked during routine maintenance. This includes checking the wiring and connections of these sensors. If there is any damage, it should be repaired immediately.
Another preventive measure is to ensure that the drive-by-wire system is functioning properly. This system is responsible for controlling the throttle and is connected to the throttle pedal position sensor. If there is any issue with the drive-by-wire system, it can cause the P2138 code to appear.
It is also important to check for any Technical Service Bulletins (TSBs) related to the P2138 code. TSBs are issued by the manufacturer to address known issues with specific vehicles. If there is a TSB related to the P2138 code, it should be followed to prevent the issue from occurring.
Regular maintenance is key in preventing the P2138 code from appearing. This includes checking the wiring and connections of the throttle pedal position sensor and the throttle position sensor. It is also important to ensure that the drive-by-wire system is functioning properly. Checking for any TSBs related to the P2138 code is also recommended. By following these preventive measures, the risk of encountering the P2138 code can be significantly reduced.
Driving with a P2138 Code
If you are driving with a P2138 code, it is important to be aware of the possible risks and symptoms that may arise. The P2138 code indicates a problem with the throttle pedal position sensor and the throttle position sensor, which can lead to dangerous driving conditions if not addressed promptly.
One of the most common symptoms of a P2138 code is the vehicle entering limp mode. Limp mode is a fail-safe mode that the vehicle enters when it detects a problem with the throttle system. This mode restricts the engine’s power and speed, making it difficult to drive the vehicle. If you experience limp mode, it is advised to pull over to a safe location and turn off the engine to prevent further damage.
Another symptom of a P2138 code is the check engine light flashing. The check engine light is a warning indicator that alerts the driver of a problem with the vehicle’s system. If the light is flashing, it indicates a severe problem that requires immediate attention. Continuing to drive with a flashing check engine light can cause serious damage to the engine and other components.
Loss of power and an unresponsive accelerator pedal are also common symptoms of a P2138 code. The throttle pedal position sensor is responsible for determining the amount of pressure applied to the accelerator pedal. A malfunctioning sensor can cause the accelerator pedal to become unresponsive or cause a loss of power, making it difficult to drive the vehicle.
In some cases, a P2138 code can also cause the vehicle to stall. The engine may suddenly shut off, causing the driver to lose control of the vehicle. This can be extremely dangerous, especially if the vehicle stalls while driving at high speeds.
In conclusion, driving with a P2138 code can be dangerous and should be addressed promptly. If you experience any of the symptoms mentioned above, it is advised to pull over to a safe location and seek professional help. Continuing to drive with a P2138 code can cause severe damage to the vehicle and put the driver and passengers at risk.
Technical Service Bulletins (TSBs)
Technical Service Bulletins (TSBs) are documents that provide specific instructions for repairing a particular vehicle problem. They are issued by vehicle manufacturers to help technicians diagnose and repair problems that are not covered by a recall. TSBs are usually released when a manufacturer becomes aware of a common problem that is not safety-related.
When it comes to diagnosing and repairing the P2138 error code, TSBs can be very helpful. They provide technicians with step-by-step instructions on how to diagnose and repair the problem. TSBs can also provide valuable information about known issues that can cause the P2138 error code, such as problems with the throttle position sensor or the accelerator pedal position sensor.
By using TSBs, technicians can save time by avoiding unnecessary diagnostic steps and repairs. TSBs can also help ensure that repairs are accurate on the first attempt, which can increase customer satisfaction and reduce the risk of comebacks.
It is important to note that TSBs are not a substitute for a proper diagnosis. They are simply a tool that can be used to help diagnose and repair a problem. If a technician is unsure about how to proceed with a repair, they should consult the appropriate TSB and seek guidance from a more experienced technician or service advisor.
In summary, TSBs can be a valuable resource when diagnosing and repairing the P2138 error code. They provide detailed instructions on how to diagnose and repair the problem, and can help ensure that repairs are accurate on the first attempt. However, they should be used in conjunction with a proper diagnosis and should not be relied upon as the sole source of information.
Conclusion
In conclusion, the P2138 code is a common issue that occurs in vehicles with electronic throttle control systems. It is caused by a malfunction in the throttle or pedal position sensor, resulting in a correlation error between the two sensors.
The symptoms of this error include a Check Engine Light (CEL), decreased acceleration, and a reduction in overall engine performance. To diagnose the issue, a test drive is recommended to check for any changes in engine performance.
To fix the P2138 code, it is essential to check the wiring and connections of the throttle and pedal position sensors. The estimated repair time for this fault code is 1.0 hour, and the cost of fixing this issue can range from $75 to $150 per hour, depending on the auto repair shop.
The Engine Control Module (ECM) or Powertrain Control Module (PCM) is responsible for detecting the correlation error between the two sensors. If the ECM or PCM detects that the signals from the two throttle position sensors do not correlate, it triggers the P2138 code.
Overall, it is crucial to address the P2138 code as soon as possible to prevent further damage to the vehicle. If left unaddressed, this issue can lead to more severe engine problems and costly repairs.
Frequently Asked Questions
What steps are involved in resolving the P2138 error code?
Resolving the P2138 error code involves diagnosing and fixing the underlying issue. The first step is to identify the cause of the error code, which is often related to a problem with the throttle pedal position sensor or the throttle position sensor. Once the cause of the error code has been identified, the necessary repairs can be made to fix the issue.
Is it possible for a contaminated throttle body to trigger the P2138 code?
Yes, a contaminated throttle body can trigger the P2138 code. If the throttle body is contaminated with dirt, debris, or other contaminants, it can cause the throttle pedal position sensor to malfunction, which can trigger the P2138 error code.
What is the correct procedure to reset a throttle position sensor?
The correct procedure for resetting a throttle position sensor varies depending on the make and model of the vehicle. In general, the throttle position sensor can be reset by disconnecting the battery for a few minutes and then reconnecting it. However, it is important to consult the vehicle’s owner’s manual or a qualified mechanic for specific instructions on how to reset the throttle position sensor.
What are the common reasons for a throttle pedal position sensor failure?
The common reasons for a throttle pedal position sensor failure include wear and tear, damage to the sensor, and electrical issues. Over time, the sensor can become worn or damaged, which can cause it to malfunction. Electrical issues can also cause the sensor to fail, such as a faulty wiring harness or a damaged connector.
Could a P2138 code indicate a serious issue with my vehicle?
Yes, a P2138 code could indicate a serious issue with your vehicle. The code is often related to a problem with the throttle pedal position sensor or the throttle position sensor, which can affect the performance and safety of the vehicle. It is important to have the issue diagnosed and repaired as soon as possible to prevent further damage and ensure the safety of the vehicle.
Are there any DIY fixes for the P2138 throttle pedal position sensor correlation error?
While there are some DIY fixes that may work for the P2138 error code, it is generally recommended to have the issue diagnosed and repaired by a qualified mechanic. Attempting to fix the issue yourself can be dangerous and may cause further damage to the vehicle. It is important to consult the vehicle’s owner’s manual or a qualified mechanic for specific instructions on how to fix the issue.
