2012 BMW 335is Has A Vacuum Leak

Diagnosing Vacuum Leaks in Your 2012 BMW 335is: Symptoms, Causes, and Repair Solutions

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Leaking Vacuum Hoses
0%
30% chance it's the
Leaking Gaskets and Seals
0%
20% chance it's the
Bad Actuators and Valves
0%
10% chance it's
Something else
The most common reasons a 2012 BMW 335is has a vacuum leak are leaking vacuum hoses, leaking gaskets and seals, or bad actuators and valves.
  • Leaking Vacuum Hoses: A cracked or disconnected vacuum hose can lead to a loss of engine vacuum, resulting in poor engine performance and increased fuel consumption.
  • Leaking Gaskets and Seals: Aged or damaged gaskets and seals can lead to fluid leaks, resulting in loss of engine oil or coolant and potential engine damage.
  • Bad Actuators and Valves: A malfunctioning actuator or valve can disrupt the proper operation of the vehicle's systems, leading to issues such as poor engine performance or erratic behavior of components like the HVAC system.
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 2012 BMW 335is has a vacuum leak?

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.

Problems with the intake manifold gasket can create the following symptoms:

  • Illuminated check engine light
  • Erratic engine performance
  • Oil and coolant leaks
  • Poor gas mileage
  • Stalling

» LEARN MORE: Intake manifold gasket symptoms

A bad valve cover gasket will result in an oil leak. You may notice oil under the car or on other parts under the hood. You might also notice a burning smell while driving.

» LEARN MORE: Signs of a bad valve cover gasket

Any time there is an emissions fault the check engine light will be displayed. The purpose of the check engine light is to inform the driver that an emission related fault has been found, and that there are on-board diagnostic (OBD) trouble codes stored in the powertrain or engine control module. Additionally, since the emissions systems are so intertwined into engine control and transmission control systems, symptoms may include nearly any sort of drivability concerns. This may include harsh shifting, failure to shift, hesitation on acceleration, jerking, engine failure to start or run, loss of power, or any number of other drivability issues.

What are the steps to diagnose a vacuum leak in a 2012 BMW 335is?

To effectively diagnose a vacuum leak in your 2012 BMW 335is, begin with a thorough visual inspection of all vacuum hoses, gaskets, and seals. Look for any visible signs of wear, cracks, or disconnections that could indicate a leak. If the visual check does not reveal any issues, proceed to perform a smoke test, which involves introducing smoke into the intake system to pinpoint where it escapes, thus identifying the leak's location. Pay close attention to any hissing sounds or unusual suction noises while the engine is running, as these can also signal a vacuum leak. Additionally, monitor the Check Engine Light, as its illumination can be a common symptom of such leaks. After conducting these initial assessments, if you suspect a leak but cannot locate it, consider testing from the other end of the system to ensure all potential leaks are identified. This methodical approach not only helps in accurately diagnosing the issue but also prioritizes repairs based on the severity and location of the leak, making it easier for you to tackle the problem effectively.

What are the common causes and symptoms of a vacuum leak in a 2012 BMW 335is?

When diagnosing a vacuum leak in a 2012 BMW 335is, it's crucial to understand the common problems that can arise within the vehicle's vacuum system. A primary issue is the presence of damaged or disconnected vacuum hoses, which are susceptible to wear and tear due to the engine's heat. Additionally, worn-out seals and gaskets can contribute to leaks, compromising the system's integrity. Another potential problem is the breakage of fittings that connect the vacuum hoses, leading to disconnections and further leaks. Recognizing the symptoms of a vacuum leak is equally important; drivers may notice the Check Engine Light illuminating, unusual hissing or suction sounds from the engine, or a high idle RPM. These signs can indicate that the engine is struggling to maintain proper airflow, resulting in rough acceleration and decreased fuel efficiency. Addressing these issues promptly is essential to prevent more significant engine damage and maintain the performance of your BMW 335is. If you suspect a vacuum leak, seeking professional assistance for a thorough diagnosis and repair is highly recommended.

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2012 BMW 335is Vacuum Leak: Causes & Repair Options