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P155D 2018 GMC Sierra Code - Hill Descent Control Message Counter Incorrect

Quick Answer

The P155D diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that the Hill Descent Control Message Counter is incorrect. Common causes include Faulty HDC module or sensor, Wiring issues or electrical connection problems, Software glitches or calibration errors. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P155D 2018 GMC Sierra indicates Hill Descent Control Message Counter Incorrect.
Common causes
Common causes include Faulty HDC module or sensor, Wiring issues or electrical connection problems, Software glitches or calibration errors.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 18, 2024
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Code P155D 2018 GMC Sierra Description

The P155D diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates that the Hill Descent Control Message Counter is incorrect. Hill Descent Control (HDC) is a feature that assists the driver when descending steep grades by automatically applying the brakes to maintain a controlled speed. The message counter tracks the number of times the HDC system has been activated and is used for diagnostic purposes. When the message counter is incorrect, it means that the system may not be accurately recording the number of times HDC has been used, which can lead to potential issues with the system's performance and reliability.

OBDII Code P155D 2018 GMC Sierra - Hill Descent Control Message Counter Incorrect
P155D 2018 GMC Sierra Code - Hill Descent Control Message Counter Incorrect

Common Causes of P155D 2018 GMC Sierra

  1. Faulty HDC module or sensor.
  2. Wiring issues or electrical connection problems.
  3. Software glitches or calibration errors.
  4. Environmental factors such as moisture or debris affecting sensor performance.

Symptoms of P155D 2018 GMC Sierra

  1. Illumination of the HDC warning light on the instrument cluster.
  2. Inconsistent or erratic behavior of the HDC system during descent.
  3. Loss of HDC functionality or inability to engage the system.
  4. Diagnostic trouble code P155D stored in the vehicle's computer system.

How to Fix P155D 2018 GMC Sierra

  1. Begin by performing a thorough inspection of the HDC system, including the module, sensor, wiring, and connections.
  2. Use a diagnostic scan tool to retrieve the specific details of the P155D code and any related codes for further troubleshooting.
  3. Test the HDC system to verify its functionality and identify any discrepancies in the message counter.
  4. If necessary, replace the faulty HDC module, sensor, or repair any wiring issues to correct the message counter inaccuracy.
  5. Clear the DTCs from the vehicle's computer system and perform a final test drive to ensure the HDC system operates correctly.

Cost to Fix P155D 2018 GMC Sierra

The cost of repairing a P155D code on a 2018 GMC Sierra can vary depending on the specific cause of the issue and the required repairs. In general, the parts and labor for replacing a faulty HDC module or sensor, addressing wiring problems, and recalibrating the system can range from $200 to $800. Additional costs may apply if software updates or reprogramming are necessary. It is recommended to consult with a qualified mechanic or dealership for a more accurate estimate based on the vehicle's condition and location. Keep in mind that labor rates and diagnostic fees can vary, so it's advisable to inquire about these costs before proceeding with the repair.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P155D 2018 GMC Sierra Code

1. What does OBDII code P155D on a 2018 GMC Sierra mean?

The code P155D specifically relates to the Hill Descent Control Message Counter Incorrect in a 2018 GMC Sierra.

2. What are the common symptoms associated with OBDII code P155D in a 2018 GMC Sierra?

Common symptoms include the illumination of the Check Engine Light, a message related to Hill Descent Control appearing on the dashboard, and potential issues with the vehicle's traction control system.

3. What can cause the OBDII code P155D to trigger in a 2018 GMC Sierra?

The code P155D is typically triggered when there is a discrepancy or error detected in the message counter related to the Hill Descent Control system.

4. How serious is the OBDII code P155D in a 2018 GMC Sierra?

While the code itself may not directly impact the drivability of the vehicle, it is important to address the underlying issue to ensure proper functionality of the Hill Descent Control system and other related systems.

5. How can I diagnose the OBDII code P155D in my 2018 GMC Sierra?

Diagnosis of the code P155D may require the use of a diagnostic scanner to retrieve the specific fault codes and perform further troubleshooting to pinpoint the exact cause.

6. Can I still drive my 2018 GMC Sierra with the OBDII code P155D present?

It is generally safe to drive the vehicle with the code P155D, but it is recommended to have the issue addressed as soon as possible to prevent any potential complications with the Hill Descent Control system.

7. What are some possible repair tips for resolving the OBDII code P155D in a 2018 GMC Sierra?

Repair tips may include checking and resetting the message counter, inspecting the wiring and connections related to the Hill Descent Control system, and ensuring proper functionality of the system components.

8. Is it necessary to visit a professional mechanic to fix the OBDII code P155D in a 2018 GMC Sierra?

While some DIY enthusiasts may attempt to troubleshoot and repair the issue themselves, consulting a professional mechanic with experience in GMC vehicles is recommended for an accurate diagnosis and proper resolution.

9. Are there any recalls or technical service bulletins related to the OBDII code P155D in a 2018 GMC Sierra?

It is advisable to check with the manufacturer or authorized GMC service centers for any recalls or technical service bulletins related to the code P155D to see if there are known solutions or remedies available.

10. How can I prevent the OBDII code P155D from reoccurring in my 2018 GMC Sierra?

Regular maintenance, such as ensuring proper system checks and addressing any related issues promptly, can help prevent the code P155D from reoccurring in the future.

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