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P143A GMC Code - Reductant Control System Diagnostic Signal Message Counter Incorrect

Quick Answer

The P143A GMC code indicates that there is a problem with the Reductant Control System Diagnostic Signal Message Counter being incorrect. Common causes include Faulty Reductant Control Module: A malfunctioning control module can cause incorrect signals to be sent within the system, Wiring Issues: Damaged or corroded wiring connections can disrupt communication within the system, Low DEF Fluid Levels: Insufficient Diesel Exhaust Fluid (DEF) levels can trigger this code as the system may not be able to adequately reduce emissions. 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
P143A GMC indicates Reductant Control System Diagnostic Signal Message Counter Incorrect.
Common causes
Common causes include Faulty Reductant Control Module: A malfunctioning control module can cause incorrect signals to be sent within the system, Wiring Issues: Damaged or corroded wiring connections can disrupt communication within the system, Low DEF Fluid Levels: Insufficient Diesel Exhaust Fluid (DEF) levels can trigger this code as the system may not be able to adequately reduce emissions.
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 10, 2024
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Code P143A GMC Description

The P143A GMC code indicates that there is a problem with the Reductant Control System Diagnostic Signal Message Counter being incorrect. The Reductant Control System, also known as the Selective Catalytic Reduction (SCR) system, is responsible for reducing harmful emissions by injecting a urea-based solution (AdBlue) into the exhaust stream. This solution reacts with the harmful nitrogen oxides (NOx) produced during combustion, converting them into harmless nitrogen and water vapor.

OBDII Code P143A GMC - Reductant Control System Diagnostic Signal Message Counter Incorrect
P143A GMC Code - Reductant Control System Diagnostic Signal Message Counter Incorrect

Common Causes of P143A GMC

  1. Faulty Reductant Control Module: A malfunctioning control module can cause incorrect signals to be sent within the system.
  2. Wiring Issues: Damaged or corroded wiring connections can disrupt communication within the system.
  3. Low DEF Fluid Levels: Insufficient Diesel Exhaust Fluid (DEF) levels can trigger this code as the system may not be able to adequately reduce emissions.
  4. Sensor Malfunction: A faulty NOx sensor or other sensors within the system can cause inaccurate readings and trigger the code.

Symptoms of P143A GMC

  1. Check Engine Light: The most common symptom of this code is the illumination of the Check Engine Light on the dashboard.
  2. Reduced Fuel Efficiency: A malfunctioning Reductant Control System can lead to decreased fuel efficiency as the engine may not be running optimally.
  3. Failed Emissions Test: If the system is not functioning properly, it may cause the vehicle to fail emissions testing.
  4. Poor Performance: The vehicle may experience a decrease in performance or responsiveness due to the incorrect signals being sent to the engine.

How to Fix P143A GMC

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific error codes and pinpoint the exact cause of the problem.
  2. Inspect Wiring and Connections: Check all wiring and connections related to the Reductant Control System for any damage or corrosion. Repair or replace as necessary.
  3. Check DEF Fluid Levels: Ensure that the DEF tank is filled to the appropriate levels. Refill if necessary.
  4. Test and Replace Sensors: Test the NOx sensor and other relevant sensors to determine if they are functioning properly. Replace any faulty sensors.
  5. Clear Codes and Test Drive: After making the necessary repairs, clear the error codes and test drive the vehicle to ensure that the issue has been resolved.

Cost to Fix P143A GMC

The cost of repairing a P143A GMC code can vary depending on the specific cause of the issue. In general, the cost of parts for this repair can range from $100 to $500, with labor costs typically adding another $100 to $200. Keep in mind that the cost of diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's recommended to consult with a professional mechanic to get a more accurate estimate based on your specific situation.

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Information for Specific GMC Models

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 P143A GMC Code

What does the OBDII code P143A mean for my GMC?

The OBDII code P143A indicates that there is an issue with the reductant control system, specifically that the diagnostic signal message counter is incorrect, which can affect the performance of the emissions control system.

What symptoms might I experience with the P143A code?

Common symptoms include reduced engine performance, a warning light on the dashboard, and potential issues with the vehicle's emissions system, which could lead to increased emissions.

What are the common causes of the P143A code?

The P143A code can be triggered by issues such as a malfunctioning reductant control module, faulty wiring or connectors in the reductant system, or software issues in the vehicle's engine control module (ECM).

How can I diagnose the P143A code?

To diagnose the P143A code, use an OBDII scanner to confirm the code, inspect the reductant control system for any physical damage, check wiring and connectors for faults, and consider updating the vehicle's ECM software if applicable.

What repairs are recommended for the P143A code?

Repairs may include replacing the reductant control module, repairing any damaged wiring or connectors, and reprogramming or updating the ECM if necessary. Always address any underlying issues causing the code to appear.

Can I drive my GMC with the P143A code?

While it may be possible to drive the vehicle, it is not recommended as it could lead to decreased performance and increased emissions, potentially causing further damage to the vehicle’s emissions system.

Will clearing the P143A code fix the problem?

Clearing the code may temporarily remove the warning light, but it will not fix the underlying issue. The code is likely to return if the root cause is not addressed.

Is the P143A code serious?

Yes, the P143A code can indicate a problem with the emissions control system, which can lead to increased emissions and potential legal issues related to emissions compliance, so it should be diagnosed and repaired promptly.

Can I fix the P143A code myself?

If you have experience with automotive repairs and diagnostics, you may be able to troubleshoot and fix the issue by inspecting the reductant control system and making necessary repairs. Otherwise, it’s advisable to consult a professional mechanic.

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