Engine-Codes.com
Engine-Codes – GMC – P1056 GMC

P1056 GMC Code - Reductant Pump Low Speed

Quick Answer

The P1056 GMC code refers to a Reductant Pump Low Speed error in the vehicle's emission control system. Common causes include Faulty Reductant Pump: The most common cause of a P1056 code is a malfunctioning or failing reductant pump, Wiring Issues: Problems with the wiring harness or connectors associated with the reductant pump can also trigger this error code, Software or Calibration Issues: Issues with the vehicle's engine control module (ECM) software or calibration can lead to a Reductant Pump Low Speed error. 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
P1056 GMC indicates Reductant Pump Low Speed.
Common causes
Common causes include Faulty Reductant Pump: The most common cause of a P1056 code is a malfunctioning or failing reductant pump, Wiring Issues: Problems with the wiring harness or connectors associated with the reductant pump can also trigger this error code, Software or Calibration Issues: Issues with the vehicle's engine control module (ECM) software or calibration can lead to a Reductant Pump Low Speed error.
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
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P1056 GMC Description

The P1056 GMC code refers to a Reductant Pump Low Speed error in the vehicle's emission control system. The reductant pump is a crucial component in the Selective Catalytic Reduction (SCR) system, which is responsible for reducing harmful emissions from the vehicle's exhaust. The reductant pump is tasked with supplying the necessary urea solution (AdBlue) to the SCR system to facilitate the conversion of harmful nitrogen oxides (NOx) into nitrogen gas and water vapor, which are less harmful to the environment.

OBDII Code P1056 GMC - Reductant Pump Low Speed
P1056 GMC Code - Reductant Pump Low Speed

Common Causes of P1056 GMC

  1. Faulty Reductant Pump: The most common cause of a P1056 code is a malfunctioning or failing reductant pump.
  2. Wiring Issues: Problems with the wiring harness or connectors associated with the reductant pump can also trigger this error code.
  3. Software or Calibration Issues: Issues with the vehicle's engine control module (ECM) software or calibration can lead to a Reductant Pump Low Speed error.
  4. Low Urea Levels: Insufficient urea solution (AdBlue) in the reductant tank can also cause issues with the reductant pump operation.

Symptoms of P1056 GMC

  1. Check Engine Light: The most common symptom associated with the P1056 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A malfunctioning reductant pump can lead to decreased fuel efficiency as the SCR system may not be operating optimally.
  3. Poor Performance: The vehicle may experience a decrease in overall performance, including reduced power and acceleration.
  4. Increased Emissions: A faulty reductant pump can result in higher emissions output, which may be noticeable during emissions testing or through visible exhaust emissions.

How to Fix P1056 GMC

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific error code and determine the cause of the Reductant Pump Low Speed error.
  2. Inspect Reductant Pump: Check the reductant pump for any signs of damage or wear. Replace the pump if necessary.
  3. Check Wiring: Inspect the wiring harness and connectors associated with the reductant pump for any damage or corrosion. Repair or replace as needed.
  4. Refill Urea Tank: Ensure that the urea tank is filled with an adequate amount of urea solution (AdBlue) to facilitate proper operation of the reductant pump.
  5. Clear Error Code: After addressing the underlying issue, clear the error code from the vehicle's ECM to reset the check engine light.

Cost to Fix P1056 GMC

The cost of repairing a Reductant Pump Low Speed issue can vary depending on the specific cause of the problem and the labor rates at the auto repair shop. On average, the cost of replacing a faulty reductant pump can range from $300 to $800, including parts and labor. However, additional costs may be incurred if wiring repairs or software calibrations are necessary. It is recommended to consult with a professional mechanic to receive an accurate estimate based on the vehicle's make and model. Labor rates typically range from $80 to $150 per hour, but rates may vary depending on location and the repair shop.

Need more information about the P1056 GMC code?

Need more information on how to fix the P1056 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1056 GMC code diagnosed by a professional: Find a repair shop in your area

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 P1056 GMC Code

1. What does the OBDII code P1056 mean on a GMC?

P1056 indicates "Reductant Pump Low Speed," which means the reductant (DEF) pump is not operating at the expected speed, potentially affecting the SCR (Selective Catalytic Reduction) system.

2. What are the common symptoms of the P1056 code in a GMC vehicle?

Symptoms may include a check engine light, DEF system warning messages, reduced engine performance, or the vehicle entering a limited power mode.

3. What causes the P1056 code to appear on a GMC?

Common causes include a faulty reductant pump, electrical issues like damaged wiring or connectors, a clogged DEF filter, or a failed reductant control module.

4. Can I drive my GMC with a P1056 code?

While you may be able to drive the vehicle, prolonged use with this code can lead to reduced engine performance or emissions compliance issues. It's best to address it promptly.

5. How is the P1056 code diagnosed in a GMC?

A technician will use a scan tool to confirm the code, inspect the reductant pump, check wiring and connectors for damage, and test the system's operation.

6. How do I fix the P1056 code on my GMC?

Repairs may involve replacing the reductant pump, repairing damaged wiring or connectors, cleaning the DEF system, or reprogramming the reductant control module.

7. Can a clogged DEF filter cause the P1056 code?

Yes, a clogged DEF filter can restrict the flow of reductant, potentially causing the pump to operate at low speed and trigger the P1056 code.

8. What tools are needed to troubleshoot the P1056 code on a GMC?

A diagnostic scan tool, a multimeter for electrical testing, and tools to access and inspect the reductant pump and DEF system are typically required.

9. Is the P1056 code covered under warranty for my GMC?

This depends on your warranty coverage and vehicle age. Emissions-related components, such as the reductant system, may be covered under the emissions warranty.

10. Can low-quality DEF cause the P1056 code on a GMC?

Yes, using poor-quality or contaminated DEF can lead to system malfunctions, including reductant pump performance issues that may trigger the P1056 code.

Discuss the causes and fixes for P1056 GMC OBDII Code

Submit a New Comment

Code P1056 GMC comments

No comments found for this page.