2021 Ram ProMaster City Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2021 Ram ProMaster City and How to Resolve Them

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Reviewed by
Andrew Hajjar
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 2021 Ram ProMaster City 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 2021 Ram ProMaster City 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.

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.

Customers with drum brake systems often specify they have lost braking power, or that the vehicle's brakes are making noise. This is because brake drums do not dissipate heat very well, so the heat from hard braking will cause stress fractures. These fractures make can make noise on the brake shoes as the drum revolves around the shoes. Lastly, the brake shoes may not be problematic, but may cause a grinding noise while stopping. This would indicate the shoes have no braking material left, and the brake shoes must be changed before the vehicle can be safely driven.

Learn more about brake shoe symptoms

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 2021 Ram ProMaster City?

When faced with a rough idle in your 2021 Ram ProMaster City, it's essential to approach the diagnosis methodically. Start by checking for fault codes using a diagnostic scanner, as these codes can reveal specific issues within the vehicle's computer system. Next, inspect the air filter; a dirty or clogged filter can significantly restrict airflow, leading to performance problems. If the air filter appears clean, turn your attention to the spark plugs, as worn or fouled plugs can cause misfires that contribute to a rough idle. Following this, examine the fuel system for any blockages or malfunctions, such as a clogged fuel filter or faulty injectors, which can disrupt fuel delivery. Additionally, don't overlook the throttle body; a buildup of dirt can affect the air-fuel mixture, so cleaning it may resolve the issue. Lastly, check the PCV valve, as a malfunction here can also lead to rough idling. By systematically addressing these areas, you can effectively identify and resolve the underlying causes of the rough idle in your vehicle.

What are the common problems that could cause a rough idle in a 2021 Ram ProMaster City?

When diagnosing a rough idle in a 2021 Ram ProMaster City, it's essential to explore several common problems that could be affecting your vehicle's performance. A dirty or clogged air filter is often a primary culprit, as it can significantly restrict airflow to the engine, leading to an uneven idle. Additionally, worn or faulty spark plugs may cause misfiring, which results in rough engine operation. Vacuum leaks are another potential issue, as they can disrupt the air-fuel mixture and negatively impact engine performance. Problems within the fuel system, such as a clogged fuel filter or a malfunctioning fuel pump, can hinder fuel delivery and contribute to a rough idle. Furthermore, a malfunctioning Mass Airflow Sensor (MAF) can disrupt the air-to-fuel ratio, exacerbating idle issues. Lastly, issues with the Exhaust Gas Recirculation (EGR) valve can affect the combustion process, leading to rough idling. Addressing these issues promptly is crucial for maintaining optimal vehicle performance and preventing further damage. If you're experiencing a rough idle, consider these common problems as potential starting points for your DIY troubleshooting efforts.

How urgent is it to address the rough idle in my 2021 Ram ProMaster City?

When it comes to addressing a rough idle in your 2021 Ram ProMaster City, understanding the urgency of the situation is crucial for maintaining your vehicle's performance and longevity. A rough idle can indicate serious engine issues, such as misfiring cylinders or fuel system malfunctions, which, if left unchecked, may lead to more extensive and costly repairs. Additionally, a rough idle can negatively impact your fuel efficiency, causing you to spend more on gas over time. For those who enjoy DIY projects, it’s essential to recognize that this issue can also affect the overall driveability of your vehicle, leading to vibrations and potential stalling that could compromise your safety on the road. While it may not seem like an immediate emergency, addressing a rough idle promptly can prevent minor issues from escalating into major problems. If you're comfortable with basic automotive diagnostics, consider checking for error codes or inspecting components like spark plugs and fuel injectors. However, for a thorough diagnosis, consulting a professional mechanic is advisable to ensure that you accurately identify and resolve the underlying cause of the rough idle. Taking these steps not only enhances your driving experience but also safeguards your investment in your vehicle.

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