2010 BMW 335i Has Rough Idle

Common Causes of Rough Idling in Your 2010 BMW 335i and How to Resolve Them

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Reviewed by

Andrew Hajjar

Written by RepairPal Car Genius

Updated January 14, 2025

21% chance it's the

Spark Plugs

15% chance it's the

Ignition Coil

64% chance it's

Something else

The most common reasons a 2010 BMW 335i has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.

Spark Plugs: A worn or fouled spark plug can cause misfires, rough idling, and decreased fuel efficiency due to incomplete combustion.
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.

What are the best BMW repair shops?

RepairPal Certified shops can diagnose and repair your 2010 BMW 335i engine and performance issues. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.

How much does it cost to fix a 2010 BMW 335i 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:

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.
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.
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.
Brake pads look thin: You may be able to visually check your brake pad thickness to determine if they need replacement.

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 common problems that could cause a rough idle in a 2010 BMW 335i?

When diagnosing a rough idle in a 2010 BMW 335i, it's essential to consider several common problems that could be affecting the vehicle's performance. One of the primary culprits is faulty spark plugs, which can lead to misfires and an unsteady idle. Additionally, issues with the turbocharger may arise if it is drawing air from incorrect sources, bypassing the Mass Air Flow (MAF) sensor, resulting in similar symptoms. The eccentric shaft sensor is another critical component; if it malfunctions, it can cause rough idling, particularly noticeable at start-up. Furthermore, the PCV valve, which is part of the valve cover, can contribute to rough idling and stalling if it fails. Fuel delivery issues, such as leaking fuel injectors, are also prevalent in the BMW 335i, and the manufacturer has acknowledged this problem, offering warranties for the N54 fuel injectors. Lastly, a failing high-pressure fuel pump (HPFP) can cause hesitation in low gears, which may also manifest as a rough idle. Addressing these issues through regular maintenance and timely repairs can significantly enhance the driving experience and prolong the life of your BMW 335i.

How urgent is it to address the rough idle in a 2010 BMW 335i?

When dealing with a rough idle in your 2010 BMW 335i, understanding the urgency of the situation is crucial for both safety and vehicle longevity. If the rough idle is only noticeable during the initial start-up and resolves itself shortly after, you may not need to act immediately. However, if the rough idle persists or worsens, especially during cold starts, it becomes imperative to address the issue without delay. Persistent rough idling can indicate underlying problems such as faulty spark plugs or fuel delivery issues, which, if left unchecked, could lead to more severe engine damage and safety risks while driving. Regular maintenance and prompt repairs not only enhance your vehicle's performance but also ensure a smoother ride, making it essential to monitor these symptoms closely and take action as needed.

Related 2010 BMW 335i Problems

Read about related problems experienced by other BMW 335i drivers like you.

BMW 335i hard starting issue due to high pressure fuel pump and fuel rail pressure sensor replacement needed

Some BMW 335i owners report experiencing hard starting issues related to the high-pressure fuel pump (HPFP) and fuel rail pressure sensor, which can manifest as long cranks during startup and the illumination of the malfunction engine light while driving. These problems may require diagnosis by a certified BMW mechanic to determine if the HPFP is the underlying cause. If low fuel pressure is detected and the pump isn't priming, owners might need to replace the entire pump assembly. In certain cases, issues like a blocked pump can be repaired, but replacement of both the high-pressure rail sensor and the updated low-pressure sensor may also be necessary. A failing HPFP can lead to unexpected stalling, particularly during idle or low-speed driving, and can result in reduced engine power, rough idling, and even complete engine failure. Therefore, accurate diagnosis and timely replacement of components are essential for resolving these serious issues.

2 model years affected

Avg Mileage: 165,083

11 others reported problem

4 comments

Jaguar XKR rough idling issue with trouble codes indicating random multiple misfire in one bank

Some Jaguar XKR owners report experiencing rough idling issues accompanied by trouble codes indicating random multiple misfires, such as P0300, P0302, and P0304, which are linked to specific cylinders like cylinder 2 and cylinder 4. These owners often identify potential causes including vacuum leaks, spark plug problems, or ignition coil failures. Additionally, some report symptoms of fuel starvation, prompting checks of fuel pressures for accurate diagnosis. Issues with the supercharger bypass valve have also been noted as a contributing factor to rough idling. Furthermore, maintaining the correct air-to-fuel ratio is crucial, as any discrepancies can exacerbate misfires and idling issues. To resolve these problems, owners may need to reset fault codes, check fuel pressure, inspect the supercharger bypass valve, and ensure optimal air-to-fuel ratios.

1 model year affected

Avg Mileage: 199,940

2 others reported problem

1 comment

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