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P20E8 2018 GMC Sierra Code - Reductant Low Pressure

Quick Answer

The P20E8 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Reductant Low Pressure system. Common causes include Low DEF fluid level, Malfunctioning reductant pump, Clogged reductant lines. 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
P20E8 2018 GMC Sierra indicates Reductant Low Pressure.
Common causes
Common causes include Low DEF fluid level, Malfunctioning reductant pump, Clogged reductant lines.
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 16, 2024
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Code P20E8 2018 GMC Sierra Description

The P20E8 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Reductant Low Pressure system. This system is a crucial component of the vehicle's emissions control system, specifically related to the selective catalytic reduction (SCR) system. The SCR system uses a reductant, typically a urea-based solution known as diesel exhaust fluid (DEF), to reduce harmful nitrogen oxides (NOx) emissions into nitrogen and water vapor.

OBDII Code P20E8 2018 GMC Sierra - Reductant Low Pressure
P20E8 2018 GMC Sierra Code - Reductant Low Pressure

Common Causes of P20E8 2018 GMC Sierra

  1. Low DEF fluid level
  2. Malfunctioning reductant pump
  3. Clogged reductant lines
  4. Faulty reductant pressure sensor
  5. Electrical issues in the reductant system

Symptoms of P20E8 2018 GMC Sierra

  1. Illuminated check engine light
  2. Reduced engine power
  3. Increased emissions
  4. Poor fuel efficiency
  5. Difficulty starting the vehicle

How to Fix P20E8 2018 GMC Sierra

  1. Check and refill DEF fluid to the appropriate level.
  2. Inspect and test the reductant pump for proper operation.
  3. Clear any clogs in the reductant lines or replace damaged lines.
  4. Test and replace the reductant pressure sensor if necessary.
  5. Check the electrical connections in the reductant system for any faults.

Cost to Fix P20E8 2018 GMC Sierra

The cost of repairing a Reductant Low Pressure issue can vary depending on the specific cause of the problem. 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 for this issue typically falls between $200 and $800. It's important to note that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and the specific repair shop. It's recommended to obtain quotes from local auto repair shops for a more accurate cost estimate.

What does this mean?

Tech Notes for P20E8 2018 GMC Sierra









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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 P20E8 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P20E8 in a 2018 GMC Sierra related to Reductant Low Pressure?

The common symptoms include the check engine light illuminating on the dashboard, reduced engine performance, and potential trouble starting the vehicle.

2. What are the possible causes of OBDII code P20E8 in a 2018 GMC Sierra indicating Reductant Low Pressure?

The code P20E8 in a 2018 GMC Sierra is typically triggered by issues such as a faulty reductant pressure sensor, a malfunctioning reductant pump, clogged reductant lines, or low DEF (diesel exhaust fluid) levels.

3. How can I diagnose the OBDII code P20E8 in my 2018 GMC Sierra related to Reductant Low Pressure?

Diagnosing code P20E8 involves checking the DEF levels, inspecting the reductant pump and sensor for any signs of damage or malfunction, and ensuring that the reductant lines are clear of any obstructions.

4. Can I continue driving my 2018 GMC Sierra with OBDII code P20E8 indicating Reductant Low Pressure?

It is not recommended to drive the vehicle with the code P20E8 active, as it may lead to further engine damage and potential emission system problems. It is advisable to address the issue promptly.

5. How can I reset the OBDII code P20E8 in my 2018 GMC Sierra after fixing the Reductant Low Pressure issue?

After addressing the underlying cause of the Reductant Low Pressure problem, you can reset the OBDII code P20E8 using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes.

6. Is it possible to repair the OBDII code P20E8 in a 2018 GMC Sierra related to Reductant Low Pressure without professional help?

While some basic checks like inspecting DEF levels can be done by the owner, diagnosing and repairing the specific components causing the code often requires professional automotive expertise.

7. What are some preventive measures to avoid OBDII code P20E8 in a 2018 GMC Sierra linked to Reductant Low Pressure?

Regularly checking and maintaining proper DEF levels, ensuring the reductant system components are functioning correctly, and using high-quality DEF can help prevent issues leading to code P20E8.

8. Are there any safety concerns associated with OBDII code P20E8 in a 2018 GMC Sierra indicating Reductant Low Pressure?

While the code itself may not pose immediate safety risks, ignoring the underlying issue causing Reductant Low Pressure can result in reduced engine performance and potential emission system problems, impacting vehicle safety and efficiency.

9. How long does it typically take to repair OBDII code P20E8 in a 2018 GMC Sierra related to Reductant Low Pressure?

The repair time for code P20E8 can vary depending on the specific cause of the issue. Simple fixes like refilling DEF may take a short time, while diagnosing and replacing faulty components can require more extensive repair work.

10. Can extreme weather conditions affect the occurrence of OBDII code P20E8 in a 2018 GMC Sierra due to Reductant Low Pressure?

Extreme temperatures can potentially impact the DEF solution and reductant system components, leading to issues with Reductant Low Pressure and triggering code P20E8. It's essential to monitor the system's performance in varying weather conditions.

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