2018 Ram ProMaster 2500 Has Rough Idle

Diagnosing Causes of Rough Idle in Your 2018 Ram ProMaster 2500 and Solutions for a Smoother Ride

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Reviewed by
Bo Fader
Written by RepairPal Car Genius
Updated January 14, 2025
0%
21% chance it's the
Spark Plugs
0%
15% chance it's the
Ignition Coil
0%
64% chance it's
Something else
The most common reasons a 2018 Ram ProMaster 2500 has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
  • Spark Plugs: Worn or fouled spark plugs can lead to misfires, poor fuel economy, and difficulty starting the engine.
  • Ignition Coil: A faulty ignition coil can cause misfires, rough idling, and difficulty starting the engine due to inadequate spark delivery to the spark plugs.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2018 Ram ProMaster 2500 has rough idle?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Brake caliper failure occurs in two different ways, and they create different symptoms.

The caliper can become stuck, in which case it won't release the brake pads. The seized caliper will cause the vehicle to brake constantly on one side, forcing the car to move toward that side. This pulling will be accompanied by a strong odor from one wheel.

Another way calipers fail is by leaking. If the caliper leaks, the brake pedal will feel too easy to push, and will sink all the way to the floor when held. Braking will become less effective the longer this goes on. There may also be brake fluid leaking onto the wheel.

Here are a few common symptoms of worn-out brake pads:

  1. Low brake pad warning light is on: Not all vehicles are equipped with this system, but if yours is, this dashboard indicator light will likely be the first signal it’s time to replace your brake pads.
  2. Brakes start to squeal regularly: This is often one of the first signs of worn brake pads and is caused by a metallic piece built into brake pads for this exact purpose. This part contacts the brake rotor to make a squealing or whining noise when the pads are low.
  3. Brakes make loud grinding noise: If not addressed early enough, your brake pads may get so worn that the metal backing plate of the pad grinds against the metal rotor.
  4. Brake pads look thin: You may be able to visually check your brake pad thickness to determine if they need replacement.

Brake rotors are mainly maintenance free, but when they have been subjected to abnormally hard use, the heat they absorb can cause the metal to turn blue, and cracking to occur. When this occurs, customers often specify they have lost braking power, or the vehicle's brakes are making noise. There may be no symptoms at all related to changing the brake rotors, since it is recommended to change brake rotors on most modern vehicles when performing a standard brake service.

Most often, a brake system inspection will just be a routine portion of manufacturer specified maintenance, and will be performed at mileage intervals. In those cases, there will likely be no symptoms. However, when a brake system makes a funny noise, causes vibration, is hard to use, will not slow the vehicle, prevents the vehicle from driving, makes the vehicle pull to one side, or leaks brake fluid, the vehicle will need a visit dedicated to the inspection of the brake system.

What are the initial diagnostic steps to take for a rough idle in a 2018 Ram ProMaster 2500?

When faced with a rough idle in your 2018 Ram ProMaster 2500, it's essential to adopt a systematic diagnostic approach to identify and resolve the issue effectively. Start by checking for fault codes using a diagnostic scanner, as these codes can reveal specific problems within the engine's systems. Next, inspect the spark plugs for wear or fouling, as they play a crucial role in engine performance. A clean and unobstructed air filter is also vital; ensure it is free from dirt and debris to maintain proper airflow. Additionally, examine the vacuum hoses for any signs of damage or leaks, as these can disrupt the air-fuel mixture and lead to idle issues. Cleaning the throttle body is another important step, as carbon buildup can hinder its function. Finally, assess the fuel system components, including the fuel pump, filter, and injectors, to ensure they are operating correctly. By following this structured approach, you can effectively diagnose and address the rough idle, restoring your vehicle's performance.

What are the common causes of a rough idle in a 2018 Ram ProMaster 2500?

When diagnosing a rough idle in your 2018 Ram ProMaster 2500, it's crucial to consider several common problems that could be at play. One of the first areas to check is the air filter; a dirty or clogged filter can significantly restrict airflow, leading to an uneven idle. Additionally, inspect the spark plugs, as worn or faulty plugs can cause misfires, which are often felt as a rough idle. Another potential culprit is vacuum leaks, which can disrupt the air-fuel mixture and result in unstable engine performance. Fuel system issues, such as a clogged fuel filter or malfunctioning fuel injectors, can also contribute to this problem, affecting how the engine receives fuel. Don't overlook the ignition system; components like ignition coils or distributors that are failing can lead to similar symptoms. Lastly, a malfunctioning mass airflow sensor can throw off the air-fuel balance, exacerbating the rough idle. By systematically checking these components, you can identify and resolve the underlying issues, ensuring your ProMaster runs smoothly.

How urgent is it to address the rough idle in a 2018 Ram ProMaster 2500?

Addressing a rough idle in your 2018 Ram ProMaster 2500 is not just a matter of comfort; it is crucial for the vehicle's overall health and performance. A rough idle can signal underlying engine problems that, if ignored, may escalate into more severe issues, potentially leading to costly repairs. For instance, it could indicate malfunctioning spark plugs, fuel system irregularities, or sensor failures, all of which are vital for optimal engine function. Moreover, neglecting this symptom can result in decreased fuel efficiency, which not only affects your wallet but also contributes to increased emissions. Regular maintenance and prompt repairs are essential to avoid these complications, ensuring that your vehicle runs smoothly and efficiently. Therefore, if you notice a rough idle, it is advisable to investigate the cause and address it as soon as possible to maintain the longevity and reliability of your ProMaster.

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2018 Ram ProMaster 2500 Rough Idle Causes & Repairs