AutoCodes – Generic – P056D

P056D Code - Reductant Control Module System Voltage

Quick Answer

Some manufacturers are now using a Diesel Exhaust Fluid (DEF) system commonly called a Selective Catalytic Reduction (SCR) system to reduce harmful oxides of Nitrogen (NOx). Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module circuit poor electrical connection. 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: P056D indicates Reductant Control Module System Voltage.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module circuit poor electrical connection.
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.

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Code Popularity 3,569

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 25, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P056D Description

Some manufacturers are now using a Diesel Exhaust Fluid (DEF) system commonly called a Selective Catalytic Reduction (SCR) system to reduce harmful oxides of Nitrogen (NOx). The diesel exhaust fluid is a Urea based solution of approximately 32% Urea and 64% distilled water. The solution is injected into the exhaust gas stream upstream of the SCR catalyst. Once in the exhaust system it decomposes and becomes Ammonia (NH3) and Carbon dioxide (CO2). Within the catalyst the NH3 and CO2 react with the Nox to create Oxygen (O2) and harmless Nitrogen (N2).
The system requires a storage tank for the diesel exhaust fluid, a pump with integrated level sensor, pressure sensor and fluid quality sensor, an injector fitted to the exhaust system, fluid heater and the catalyst. Sensors can also be fitted close to the SCR catalyst to monitor temperature during regeneration.
The system is closely monitored for correct operation as a failure of the system will have a large impact on vehicle exhaust gas emissions of oxides of Nitrogen.

OBDII Code P056D - Reductant Control Module System Voltage - AutoCodes.com — P056D Code - Reductant Control Module System Voltage

What does this mean?

What are the Possible Causes of the DTC P056D?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC P056D?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P056D code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P056D code?

Need more information on how to fix the P056D code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P056D code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P056D Porsche — Reductant Control Module System Voltage

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 P056D Code

1. What are common symptoms of OBDII code P056D (Reductant Control Module System Voltage)?

- Common symptoms include the illumination of the Check Engine Light, reduced engine performance, and potential issues with the vehicle's emissions system.

2. What can cause OBDII code P056D to trigger?

- The code P056D can be triggered by a faulty reductant control module, wiring issues, or a low voltage condition in the reductant control module system.

3. How serious is OBDII code P056D?

- OBDII code P056D is considered a moderate severity issue. While it may not cause immediate danger, ignoring it can lead to increased emissions and potential engine performance issues.

4. How can I diagnose OBDII code P056D?

- Diagnosis typically involves using an OBDII scanner to retrieve the code, checking the reductant control module system voltage using a multimeter, and inspecting the wiring for any damage or loose connections.

5. What are the repair options for OBDII code P056D?

- Repair options may include replacing the reductant control module, repairing or replacing damaged wiring, and ensuring the system voltage is within specifications.

6. Can I drive with OBDII code P056D active?

- It is generally not recommended to drive with OBDII code P056D active, as it can lead to increased emissions and potentially affect engine performance.

7. How much does it cost to repair OBDII code P056D?

- The cost of repairing OBDII code P056D can vary depending on the underlying cause. Repairs may range from a few hundred dollars for wiring repairs to over a thousand dollars for a new reductant control module.

8. Can OBDII code P056D be triggered by a loose battery connection?

- Yes, a loose or corroded battery connection can cause a low voltage condition in the reductant control module system, triggering OBDII code P056D.

9. Will resetting the OBDII code P056D make it go away permanently?

- Resetting the code may temporarily turn off the Check Engine Light, but if the underlying issue is not addressed, the code is likely to return.

10. Is it possible to prevent OBDII code P056D from occurring?

- Regular maintenance, such as checking and cleaning battery connections, inspecting wiring for damage, and ensuring proper voltage levels, can help prevent OBDII code P056D from occurring.