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Engine-Codes – Generic – P143A

P143A Code - Reductant Control System Diagnostic Signal Message Counter Incorrect

Quick Answer

The P143A diagnostic trouble code (DTC) indicates that the reductant control system's diagnostic signal message counter is incorrect. Common causes include Faulty Reductant Control Module: A malfunctioning reductant control module can cause communication errors and trigger the P143A code, Wiring Issues: Damaged or corroded wiring connections between the reductant control system components can disrupt communication signals, Defective NOx Sensors: Faulty NOx sensors can lead to inaccurate data being transmitted to the vehicle's computer system. 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 indicates Reductant Control System Diagnostic Signal Message Counter Incorrect.
Common causes
Common causes include Faulty Reductant Control Module: A malfunctioning reductant control module can cause communication errors and trigger the P143A code, Wiring Issues: Damaged or corroded wiring connections between the reductant control system components can disrupt communication signals, Defective NOx Sensors: Faulty NOx sensors can lead to inaccurate data being transmitted to the vehicle's computer system.
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 Description

The P143A diagnostic trouble code (DTC) indicates that the reductant control system's diagnostic signal message counter is incorrect. This system is an integral part of the vehicle's emissions control system, specifically designed to reduce harmful pollutants emitted from the exhaust. The reductant control system is responsible for injecting a urea-based solution (commonly known as diesel exhaust fluid or DEF) into the exhaust stream to break down harmful nitrogen oxides (NOx) into harmless nitrogen and water vapor.

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

Common Causes of P143A

  1. Faulty Reductant Control Module: A malfunctioning reductant control module can cause communication errors and trigger the P143A code.
  2. Wiring Issues: Damaged or corroded wiring connections between the reductant control system components can disrupt communication signals.
  3. Defective NOx Sensors: Faulty NOx sensors can lead to inaccurate data being transmitted to the vehicle's computer system.
  4. Low DEF Fluid Levels: Insufficient DEF fluid in the tank can trigger the P143A code as the system may not be able to operate effectively.
  5. Software Issues: Software glitches or updates in the vehicle's computer system can sometimes cause communication errors within the reductant control system.

Symptoms of P143A

  1. Check Engine Light: The most common symptom associated with the P143A code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A malfunctioning reductant control system can lead to reduced fuel efficiency as the engine may not be operating at optimal levels.
  3. Rough Idle: The engine may experience rough idling or misfires due to incorrect signals from the reductant control system.
  4. Increased Emissions: The vehicle may emit higher levels of pollutants due to the ineffective operation of the reductant control system.
  5. Reduced Engine Performance: The vehicle may experience a decrease in power and responsiveness due to the malfunctioning emissions control system.

How to Fix P143A

  1. Diagnose the Issue: Use an OBD-II scanner to retrieve the specific DTC and pinpoint the exact cause of the problem.
  2. Check DEF Fluid Levels: Verify that the DEF fluid levels are adequate and top up if necessary.
  3. Inspect Wiring and Connections: Check the wiring and connections for any signs of damage or corrosion and repair or replace as needed.
  4. Test NOx Sensors: Test the NOx sensors to ensure they are functioning correctly and replace any faulty sensors.
  5. Reset the System: Clear the DTC and reset the vehicle's computer system to see if the issue persists after repairs have been made.

Cost to Fix P143A

The cost of repairing a P143A 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 adding an additional $100 to $300. Overall, the total repair cost can range from $200 to $800 or more, depending on the extent of the repairs needed. It's important to note that labor rates and part prices can vary significantly based on the location of the repair shop, the make and model of the vehicle, and the complexity of the repair. It's advisable to consult with a qualified mechanic to get an accurate estimate for your specific situation.

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Code P143A Information for Specific Makes

  • P143A Buick — Reductant Control System Diagnostic Signal Message Counter Incorrect
  • P143A Cadillac — Reductant Control System Diagnostic Signal Message Counter Incorrect
  • P143A Chevrolet — Reductant Control System Diagnostic Signal Message Counter Incorrect
  • P143A GMC — Reductant Control System Diagnostic Signal Message Counter Incorrect
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 Code

1. What are the common symptoms of OBDII code P143A?

- Common symptoms include the Check Engine Light being illuminated, reduced engine performance, and potential issues with emissions control.

2. What does the OBDII code P143A indicate?

- This code indicates that the Reductant Control System Diagnostic Signal Message Counter is reporting an incorrect value, potentially pointing to a problem with the system's operation.

3. What are the possible causes of OBDII code P143A?

- Possible causes include a faulty Reductant Control Module, wiring issues in the system, software glitches, or sensor malfunctions.

4. How can I diagnose the OBDII code P143A?

- Diagnosis typically involves using a scan tool to read the code, checking the Reductant Control System components for any visible damage or issues, and conducting a thorough inspection of the wiring and connectors.

5. Can I continue driving with OBDII code P143A present?

- It is generally not recommended to continue driving with this code present, as it can lead to increased emissions, reduced fuel efficiency, and potential damage to the vehicle's catalytic converter over time.

6. How can I repair OBDII code P143A?

- Repairing this code may involve replacing the Reductant Control Module, repairing any damaged wiring or connectors, updating software if necessary, or replacing faulty sensors in the system.

7. Is OBDII code P143A a serious issue?

- While the severity can vary depending on the underlying cause, it is important to address this code promptly to ensure proper emissions control and optimal engine performance.

8. Can a DIY enthusiast fix OBDII code P143A?

- Depending on the root cause, some DIY enthusiasts with the necessary tools and knowledge may be able to address this issue, but it is recommended to consult a professional mechanic for proper diagnosis and repair.

9. How much does it cost to fix OBDII code P143A?

- The cost of fixing this code can vary widely depending on the cause of the issue, the needed repairs or replacements, and labor costs. It is advisable to obtain estimates from local mechanics or repair shops.

10. How can I prevent OBDII code P143A from recurring?

- To prevent this code from recurring, it is essential to perform regular maintenance on the Reductant Control System, address any issues promptly, and follow the manufacturer's recommended service intervals for your vehicle.

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