Diagnosing & Fixing C1405 Engine Mount Solenoid Valve Open Circuit in a Porsche 991 (2012-2016 Carrera & Turbo)

Introduction

Imagine this: You’re driving your 2012-2016 Porsche 991 Carrera or Turbo, and suddenly, you feel unusual vibrations coming through the cabin. The car no longer handles as smoothly during aggressive acceleration or high-speed cornering. You check for fault codes using an OBD-II scanner, and it reveals C1405 – Engine Mount Solenoid Valve Open Circuit. What does this mean, and how do you fix it?

At AUTOTEK, we specialize in real-world diagnostics and expert vehicle troubleshooting. In this guide, we’ll explain why your Porsche’s active engine mounts may be failing, how to diagnose the issue, and the best way to fix it.

Understanding C1405 – Engine Mount Solenoid Valve Open Circuit

Porsche’s PADM (Porsche Active Drivetrain Mounts) system is designed to adjust engine mount stiffness dynamically, providing a balance between comfort and performance. If the solenoid valve inside the active engine mount fails, the engine mount loses its ability to adjust, causing excessive engine movement, vibrations, and reduced handling stability.

Common Symptoms of a Failing Active Engine Mount in a Porsche 991:

• Increased vibrations, especially at idle or low speeds
• Rough gear shifts or drivetrain movement under acceleration
• Harsh engine response when cornering or braking hard
• Reduced ride comfort, particularly on uneven roads
• Check Engine Light (CEL) or PADM system warning light

Related Porsche-Specific PADM Fault Codes

A failing active engine mount or its solenoid can trigger multiple diagnostic codes, including:

C1406 - Engine Mount Solenoid Valve Short Circuit

• Suggests an electrical failure in the dynamic engine mount system, leading to excessive engine movement.

C1408 - Malfunction in Dynamic Engine Mounts

• The PADM system detects an issue with the engine mount’s ability to adjust dynamically under load.

C1410 - Active Engine Mount Actuator Error

• The engine mount is not responding correctly to commands from the vehicle’s control module.

Related Generic OBD-II Fault Codes for Engine Mount Issues

If a failing engine mount affects the car’s overall performance, the following generic fault codes may also appear:

P1571 - Engine Mount Control Circuit Malfunction

• The ECU detects an issue with the electronic control of the active engine mounts.

P1573 - Active Engine Mount Performance Issue

• The engine mount is not providing the expected damping response, which may cause excessive vibrations.

P1580 - Engine Mount Adaptive Function Error

• The dynamic engine mount system is unable to self-adjust to driving conditions.

P1609 - Powertrain Mount System Error

• The ECU registers excessive movement of the engine and transmission due to a worn or damaged mount.

If any of these codes appear, your active engine mount may need to be replaced.

Step-by-Step Diagnosis of C1405 in a Porsche 991

Before replacing the active engine mount, follow these diagnostic steps:

Step 1: Scan for Fault Codes

• Use an OBD-II scanner to confirm C1405 or related active engine mount codes.
• If additional codes like C1406 or P1573 appear, it may indicate a severe issue with the active engine mount solenoid.

Step 2: Inspect the Engine Mounts & Wiring

• Locate the active engine mounts (usually near the front subframe or rear engine bay for the Porsche 991).
• Inspect for damaged wires, leaks, or mounting wear.
• Check for hydraulic fluid leaks, as a broken mount may leak damping fluid.

Step 3: Test the Engine Mount Solenoid Voltage

• Using a multimeter, measure the voltage supply at the active engine mount solenoid.
• If the solenoid is not receiving power or shows an open circuit, the mount is faulty.

Step 4: Check for Loose or Worn Mounts

• Physically inspect the engine mount for excessive movement.
• If the mount is loose, cracked, or leaking fluid, it needs replacement.

Step 5: Reset the Fault Code & Test Drive

• Clear the C1405 code using an OBD-II scanner.
• Drive the car under normal and aggressive conditions (acceleration, braking, and cornering).
• If the code reappears, the active engine mount is faulty.

Recommended Fix for Porsche 991 C1405 Code

If diagnosing the system confirms a faulty active engine mount, the best solution is to replace the mount.

✅ Recommended Replacement Part: Engine Mounting - Porsche 991.1 Carrera (2012-16) - 99137505911

Replacement Procedure:

1. Disconnect the battery to prevent electrical shorts.
2. Raise the vehicle and support the engine with a jack.
3. Remove the old engine mount by unbolting it from the chassis and engine.
4. Install the new engine mount and ensure proper torque specifications.
5. Reconnect the wiring harness and check solenoid connections.
6. Lower the vehicle, clear any stored fault codes, and test drive.

Similar Fault Codes & Reference

If your vehicle displays additional engine mount-related codes, here’s how they compare:

• C1406 – Engine Mount Solenoid Valve Short Circuit
• C1408 – Malfunction in Dynamic Engine Mounts
• C1410 – Active Engine Mount Actuator Error
• P1571 – Engine Mount Control Circuit Malfunction
• P1573 – Active Engine Mount Performance Issue
• P1580 – Engine Mount Adaptive Function Error
• P1609 – Powertrain Mount System Error

These codes all indicate issues with the active engine mounts, requiring sensor recalibration or replacement.

Conclusion

The C1405 fault code in a Porsche 991 Carrera or Turbo (2012-2016) is typically caused by a failing active engine mount solenoid or hydraulic failure, leading to excessive vibrations, rough gear shifts, and handling issues. Replacing the faulty dynamic engine mount can restore stability and enhance driving comfort.

If you’re experiencing this issue, consider replacing the engine mount, available on AUTOTEK. Need expert guidance? Contact us for professional support.

Need More Help?

If you have any questions or need further assistance, our team at AUTOTEK is here to help! Leave a comment below or contact us directly.