C1831 DTC Code: Explained and Decoded


In the world of automobile diagnostics, Diagnostic Trouble Codes (DTCs) play a crucial role. These codes are generated by your vehicle’s onboard computer system to indicate any potential issues or malfunctions. One such DTC is the C1831 code. In this article, we will dive deep into understanding the C1831 DTC code, its possible causes, and how to resolve it.

Understanding the C1831 DTC Code

When your vehicle’s computer detects a fault or anomaly in the system related to the electronic hydraulic control unit (HCU) or other components, it generates the C1831 DTC code. This code specifically indicates an issue with the pump motor relay circuit on the HCU assembly.

Possible Causes of the C1831 DTC Code

To diagnose and resolve the C1831 DTC code, it is essential to understand its potential causes. Here are some common culprits behind this code:

  1. Faulty Pump Motor Relay: A malfunctioning or defective pump motor relay can trigger the C1831 DTC code. This relay controls the activation of the hydraulic pump motor, and any disruption can lead to this error.

  2. Electrical Wiring Issues: Damaged or disconnected wires in the pump motor relay circuit can cause an interruption in the electrical current, resulting in the C1831 DTC code.

  3. Hydraulic Control Unit Malfunction: If the hydraulic control unit responsible for controlling the hydraulic pressure in your vehicle’s system is not functioning correctly, it can lead to the C1831 code being triggered.

Resolving the C1831 DTC Code

Now that we know the potential causes, let’s explore the steps to resolve the C1831 DTC code:

Step 1: Perform a Visual Inspection

Start by visually inspecting the wiring harness and connections associated with the pump motor relay circuit. Look for any signs of damage, loose connections, or corrosion. If any issues are identified, repair or replace the affected components.

Step 2: Test the Pump Motor Relay

Using a digital multimeter, test the continuity of the pump motor relay. Follow the manufacturer’s specifications to ensure accurate readings. If the relay is found to be faulty, replace it with a new one from a reliable source.

Step 3: Check the Hydraulic Control Unit

Inspect the hydraulic control unit for any visible signs of damage or leaks. If any issues are observed, professional assistance may be required to repair or replace the hydraulic control unit.

Step 4: Clear the DTC Code

Once the necessary repairs or replacements have been made, it is crucial to clear the stored DTC code from your vehicle’s computer system. This can be done using a diagnostic scanner tool or by disconnecting the battery for a few minutes.

Frequently Asked Questions (FAQs)

To provide further clarity, here are some frequently asked questions about the C1831 DTC code:

1. What are the symptoms of the C1831 DTC code?

Some common symptoms associated with the C1831 code include the illuminated “Check Engine” light on the dashboard, hydraulic system malfunctions, difficulty in engaging the brakes, and decreased overall braking performance.

2. Can I continue driving with the C1831 DTC code?

It is not recommended to continue driving with the C1831 DTC code without addressing the underlying issue. This code usually indicates a problem with the hydraulic control unit or pump motor relay, which can affect the braking system’s functionality, potentially compromising your safety.

3. Can I fix the C1831 DTC code myself?

While certain DIY troubleshooting steps can be taken to diagnose and resolve the C1831 DTC code, it is recommended to seek professional assistance if you are not familiar with automotive electrical systems. Professional technicians have the expertise and tools necessary to accurately diagnose and repair the issue.


The C1831 DTC code indicates a problem with the pump motor relay circuit on the HCU assembly. By understanding its causes and following the necessary steps for resolution, you can successfully address this issue. Remember to perform visual inspections, test relays, check the hydraulic control unit, and clear the DTC code after repairing the problem. If in doubt, consult a professional to ensure the proper resolution of the C1831 DTC code and maintain the optimal performance of your vehicle’s braking system.

About author


Meet Sam Mitchell, your experienced and reliable guide in the complex world of car fault codes. With a robust career spanning over 15 years as a professional car mechanic, John has the skills, knowledge, and practical experience to help you navigate car fault issues with confidence.


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