5.7 Hemi MDS Solenoid Failure Symptoms

If you own a vehicle with a 5.7 Hemi engine, you may have heard of MDS solenoid failure. This can cause a range of problems in your engine’s performance and fuel efficiency. 

In this blog post, we’ll discuss the symptoms of MDS solenoid failure, so you can recognize them early and take action to prevent further damage.

We’ll cover the most common signs of MDS solenoid failure, including rough idling, stalling, decreased fuel economy, and more. We’ll also provide tips on how to diagnose and repair this issue, so you can get your engine running smoothly again. 

If you’re experiencing any of these symptoms or simply want to be prepared for potential issues in the future, read on for a helpful guide to MDS solenoid failure symptoms.

Common MDS Solenoid Failure Symptoms

Hey buddy! I’m sure you’re curious about the symptoms of MDS solenoid failure in the 5.7 Hemi engine. The MDS (Multiple Displacement System) is a pretty nifty feature, as it can help improve fuel economy by deactivating some of the cylinders when they’re not needed. But if there’s a problem with the MDS solenoids, it can cause some issues. Let me walk you through the common symptoms to look out for.

Check Engine Light Illumination

Engine Light Illumination
  • The first sign that you might have an MDS solenoid problem is when the check engine light comes on.
  • It’s not always easy to tell right away that it’s specifically an MDS solenoid issue, but when you scan for diagnostic trouble codes (DTCs), you might find codes related to the MDS system.
  • Some common DTCs for this issue include P3401, P3409, P3425, and P3433. Keep in mind that these codes could also indicate other issues, so it’s essential to investigate further.

Decreased Fuel Efficiency

Decreased Fuel Efficiency
  • The MDS system is designed to help you save fuel by deactivating some cylinders when the engine doesn’t need full power.
  • If there’s a problem with the MDS solenoids, the system might not be working correctly, and you’ll notice a decrease in your vehicle’s fuel efficiency.
  • It’s worth paying attention to how much fuel your car is consuming, as a sudden drop in gas mileage can be a sign that the MDS solenoids aren’t functioning correctly.

Engine Performance Issues

Engine Performance Issues
  • MDS solenoid failure can also lead to noticeable engine performance issues.
    • You might experience engine misfires due to improper cylinder deactivation or activation.
    • Another sign is rough idling, where the engine feels unstable when idling or at low speeds.
    • Hesitation during acceleration could also occur, as the MDS solenoids may not be able to deactivate or reactivate cylinders smoothly.

Unusual Engine Noises

  • When an MDS solenoid fails, it can create some unusual sounds from the engine.
  • You may hear ticking or tapping noises that could indicate a problem with the solenoids themselves or with the MDS system’s operation.
  • It’s essential to get these noises checked out by a professional, as they can also signal other issues with the engine.

Engine Misfires and Rough Idling

When dealing with a vehicle, engine misfires, and rough idling can be quite concerning. Both of these issues can impact the overall performance and efficiency of your engine. Let’s take a closer look at each problem, its possible causes, and potential solutions.

Engine Misfires

Engine Misfires

An engine misfire occurs when one or more of the engine’s cylinders fail to fire correctly. This can cause the engine to run unevenly, affecting its performance, fuel efficiency, and smoothness. Some common causes of engine misfires include:

  • Faulty spark plugs: Spark plugs are responsible for igniting the air-fuel mixture in the engine. Worn or damaged spark plugs can cause misfires.
  • Bad ignition coils: Ignition coils are responsible for converting low-voltage electricity into high-voltage power required to fire the spark plugs. A failing ignition coil may not supply enough power, causing a misfire.
  • Malfunctioning fuel injectors: Fuel injectors deliver fuel to the engine cylinders. If they’re clogged or malfunctioning, they may not supply the correct amount of fuel, leading to a misfire.
  • Poor air-fuel mixture: Issues with the air intake system, such as a clogged air filter or a faulty mass airflow sensor, can disrupt the optimal air-fuel mixture, resulting in misfires.

Rough Idling

Rough Idling

Rough idling is when the engine runs unevenly or feels unstable while the vehicle is not in motion. It can make your car feel like it’s shaking or vibrating when you’re stopped at a traffic light or parked with the engine running. Some common causes of rough idling include:

  • Vacuum leaks: The engine uses vacuum pressure to regulate various systems, such as the intake manifold and power brakes. A leak in one of these systems can cause the engine to idle roughly.
  • Dirty throttle body: The throttle body controls the amount of air entering the engine. If it’s dirty or clogged, it can disrupt the air-fuel mixture, leading to rough idling.
  • Failing idle air control valve: The idle air control valve helps regulate the engine’s idle speed. If it’s malfunctioning, it can cause rough idling.
  • Worn or damaged spark plugs: As mentioned earlier, faulty spark plugs can cause misfires, which can also lead to rough idling.

To address engine misfires and rough idling, it’s essential to diagnose the root cause of the problem. This often involves checking the various components of the engine, such as the spark plugs, ignition coils, and fuel injectors. In some cases, a professional mechanic may be required to properly diagnose and repair the issue. Regular maintenance, including replacing worn parts and keeping the engine clean, can help prevent these issues and keep your engine running smoothly.

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Check Engine Light and Error Codes

The check engine light (CEL) is a critical component of your vehicle’s onboard diagnostic system. It alerts you when there’s a problem with your engine or related systems that might affect your vehicle’s performance, emissions, or fuel efficiency. When the CEL is illuminated, the engine control module (ECM) stores error codes, also known as diagnostic trouble codes (DTCs), which provide information about the issues detected. Let’s dive into more details about the check engine light and error codes.

Understanding the Check Engine Light

The check engine light is usually an orange or yellow symbol on your vehicle’s dashboard that looks like an engine. When the light comes on, it indicates that your vehicle’s ECM has detected a problem. It’s essential to address the issue as soon as possible to prevent further damage to the engine or its components.

Some common reasons for the check engine light to illuminate include:

  • Faulty oxygen sensor
  • Loose or damaged gas cap
  • Malfunctioning catalytic converter
  • Faulty mass airflow sensor
  • Failing ignition coils or spark plugs

Error Codes and Diagnosing Issues

When the check engine light is triggered, the ECM generates and stores specific error codes. These codes can be retrieved using an OBD-II (On-Board Diagnostics II) scanner, which plugs into the vehicle’s OBD-II port, usually located under the dashboard.

Error codes usually consist of a letter followed by four numbers (e.g., P0300). The letter indicates the system where the issue was detected, while the numbers provide more specific information about the problem. For example:

  • P codes refer to powertrain issues (engine, transmission, etc.).
  • C codes relate to chassis systems (ABS, suspension, etc.).
  • B codes are associated with body control systems (airbags, climate control, etc.).
  • U codes deal with network and vehicle communication issues.

Once the error codes are retrieved, a mechanic or an experienced DIYer can use this information to help diagnose the problem and determine the necessary repairs.

Clearing Error Codes and Resetting the Check Engine Light

After the issue has been resolved, the error codes can be cleared using an OBD-II scanner. This will also reset the check engine light. However, simply clearing the codes without addressing the underlying issue won’t resolve the problem, and the light will likely come back on.

In summary, the check engine light is an essential indicator that there’s an issue with your vehicle that needs attention. Retrieving error codes can help diagnose the problem and guide you toward the necessary repairs. Regular maintenance and promptly addressing issues can help prevent more severe damage to your engine or its components.

Poor Fuel Economy and Reduced Power

When driving a vehicle, it’s crucial to keep an eye on fuel consumption and overall performance. Poor fuel economy and reduced power can significantly impact your driving experience, increase fuel expenses, and even be a sign of underlying issues. Let’s discuss these problems and explore some of their possible causes and solutions.

Poor Fuel Economy

Poor fuel economy means your vehicle is consuming more fuel than it should, which can be frustrating and costly. Some common reasons for decreased fuel efficiency include:

  • Incorrect tire pressure: Under-inflated or over-inflated tires can negatively impact your vehicle’s fuel efficiency. It’s essential to check and adjust tire pressure regularly to ensure optimal fuel consumption.
  • Dirty air filter: A clogged or dirty air filter can disrupt the air-fuel mixture in the engine, leading to poor fuel economy. Regularly inspecting and replacing the air filter can help maintain proper fuel efficiency.
  • Malfunctioning oxygen sensor: A faulty oxygen sensor can send incorrect information to the engine control module (ECM), causing the engine to run with an improper air-fuel mixture, leading to poor fuel economy.
  • Excessive idling: Leaving your engine running while stationary can consume more fuel than you might think. Limiting idling time can help improve your fuel efficiency.

Reduced Power

Reduced power can make your vehicle feel sluggish, unresponsive, or slow to accelerate. Some common causes of reduced engine power include:

  • Clogged fuel injectors: Fuel injectors that are dirty or clogged can restrict the flow of fuel to the engine, resulting in reduced power. Regular fuel injector cleaning or replacement can help prevent this issue.
  • Faulty throttle body: A malfunctioning throttle body can disrupt the flow of air into the engine, affecting power output. Cleaning or replacing a damaged throttle body can help restore engine power.
  • Worn spark plugs or ignition coils: As previously mentioned, worn or faulty spark plugs and ignition coils can cause engine misfires, which can lead to reduced power. Regularly inspecting and replacing these components can help maintain optimal engine performance.
  • Failing fuel pump: A weak or malfunctioning fuel pump may not supply enough fuel to the engine, causing a drop in power output. Replacing a faulty fuel pump can help restore proper engine power.

To address poor fuel economy and reduced power, it’s important to diagnose and resolve the underlying causes. Regular maintenance, including inspecting and replacing worn or damaged components, can help ensure your vehicle continues to operate efficiently and with optimal performance. In some cases, it may be necessary to consult a professional mechanic to diagnose and repair more complex issues.

How to tell if your HEMI engine bad

How to Repair and Maintain Your Vehicle

Regular repair and maintenance are essential to keep your vehicle running smoothly and efficiently. A well-maintained vehicle will provide better performance, fuel economy, and longevity. Here are some general guidelines for repairing and maintaining various aspects of your vehicle.

1. Engine and Transmission

  • Change engine oil and oil filters according to the manufacturer’s recommended intervals.
  • Check and replace air filters regularly to ensure optimal engine performance.
  • Inspect and replace fuel filters periodically to prevent clogging and maintain fuel efficiency.
  • Check and change transmission fluid as recommended in your vehicle’s owner’s manual.
  • Replace worn or damaged spark plugs and ignition coils to avoid engine misfires and ensure smooth operation.
  • Check the timing belt or chain and replace it as specified in your service manual to prevent serious engine damage.
  • Regularly inspect the serpentine belt for wear or damage, and replace it when necessary to avoid accessory system failures.

2. Braking System

  • Check and replace brake pads and shoes as needed, ensuring optimal braking performance and safety.
  • Inspect brake rotors and drums for wear or warping, and resurface or replace them if necessary.
  • Regularly check and top up brake fluid levels to maintain proper hydraulic pressure in the braking system.
  • Inspect and replace worn or damaged brake lines and hoses to prevent fluid leaks and ensure reliable braking.

3. Suspension and Steering

  • Inspect and replace worn or damaged suspension components, such as shocks, struts, and bushings, to maintain a comfortable and safe ride.
  • Check and adjust tire pressure regularly to ensure optimal fuel efficiency and tire lifespan.
  • Rotate tires periodically to promote even tire wear and extend their life.
  • Check wheel alignment and have it adjusted if necessary to prevent uneven tire wear and improve handling.
  • Inspect and replace worn or damaged steering components, such as tie rods, ball joints, and control arms, to maintain proper handling and steering control.

4. Cooling System

  • Flush and refill the coolant periodically to prevent rust, corrosion, and buildup in the cooling system.
  • Inspect and replace worn or damaged hoses, clamps, and other cooling system components to prevent coolant leaks and overheating.
  • Check and replace the thermostat if necessary to ensure proper engine temperature regulation.
  • Inspect and clean or replace the radiator as needed to maintain efficient heat dissipation and prevent overheating.

5. Electrical System

  • Check and replace the battery to ensure reliable starting and electrical system operation.
  • Inspect and replace worn or damaged alternators, starters, and other electrical components to prevent system failures.
  • Regularly check and replace damaged fuses or relays to maintain proper electrical system function.

6. Exhaust System

  • Inspect the exhaust system for leaks, damage, or rust, and repair or replace components as needed to maintain proper exhaust flow and emissions control.
  • Replace the catalytic converter if it’s clogged or damaged to ensure proper emissions reduction and maintain engine performance.

These are just a few general guidelines for repairing and maintaining your vehicle. Always refer to your vehicle’s owner’s manual or service manual for specific maintenance intervals and procedures. Regularly addressing potential issues and keeping up with maintenance will help ensure your vehicle remains in good condition, providing you with reliable transportation for years to come. If you’re unsure about a repair or maintenance task, consult a professional mechanic for guidance and assistance.

5.7 Hemi MDS Solenoid Failure Symptoms


What is the MDS system in a 5.7 Hemi engine?

The Multiple Displacement System (MDS) is a fuel-saving technology used in Chrysler’s 5.7 Hemi engines. It allows the engine to deactivate four of its eight cylinders under certain driving conditions, such as cruising at a steady speed or during light load conditions, thereby improving fuel efficiency.

What are the common symptoms of a failing MDS solenoid in a 5.7 Hemi engine?

Some common symptoms of a failing MDS solenoid include engine misfires, rough idling, poor fuel economy, reduced power, and an illuminated check engine light with associated error codes.

How can I diagnose a faulty MDS solenoid?

To diagnose a faulty MDS solenoid, you can use an OBD-II scanner to read the stored diagnostic trouble codes (DTCs). MDS-related error codes include P3401, P3409, P3425, and P3433, among others. Additionally, a visual inspection of the MDS solenoids and related components can help identify any visible damage or wear.

How do I replace a faulty MDS solenoid in a 5.7 Hemi engine?

To replace a faulty MDS solenoid, you will need to locate the solenoids on the engine block, remove any obstructing components such as the intake manifold or valve covers, disconnect the electrical connector, remove the retaining bolt, and carefully remove the faulty solenoid. Then, install the new solenoid, reassemble the engine components, and clear any stored error codes using an OBD-II scanner.

How often should I check or replace MDS solenoids in my 5.7 Hemi engine?

There is no specific maintenance interval for checking or replacing MDS solenoids. However, if you experience any of the common symptoms mentioned above or receive MDS-related error codes, it’s essential to address the issue and replace the faulty solenoid as needed.


In conclusion, the MDS (Multiple Displacement System) in 5.7 Hemi engines is a crucial component designed to improve fuel efficiency and reduce emissions. However, like any other part, MDS solenoids can experience failures, which can lead to noticeable symptoms such as engine misfires, rough idling, poor fuel economy, reduced power, and illuminated check engine lights.

Being aware of these symptoms and addressing them promptly is essential for maintaining your vehicle’s performance, fuel efficiency, and overall health. Diagnosing and replacing faulty MDS solenoids is a crucial step in resolving these issues and ensuring your engine continues to operate at its best. While some drivers may be able to tackle this task themselves, others might benefit from consulting a professional mechanic for guidance and assistance.

By understanding the symptoms of MDS solenoid failure and taking timely action, you can protect your investment, maintain optimal performance, and extend the life of your 5.7 Hemi engine.

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