SKU: 69785357549

034Motorsport PCV Breather Hose Upgrade - Audi B9 S4/S5/SQ5 3.0TFSI - 034-101-3108

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Description

034Motorsport PCV Breather Hose Upgrade - Audi B9 S4/S5/SQ5 3.0TFSI - 034-101-3108034 Motorsport PCV Breather Hose Upgrade Audi B9 S4 S5 SQ5 3. 0TFSI 034 101 3108. CURRENTLY ON BACK ORDER AT 034 MOTORSPORT WITH NO ETA Upgrade your failure prone PCV breather hose with the high performance, reliable 034Motorsport PCV Breather Hose, engineered for enhanced durability and long lasting performance. The 034Motorsport PCV Breather Hose isn't just an upgrade for tuned vehicles it's also a critical safety enhancement for all EA839 equipped

034 Motorsport - PCV Breather Hose Upgrade - Audi B9 S4/S5/SQ5 3.0TFSI - 034-101-3108.

CURRENTLY ON BACK ORDER AT 034 MOTORSPORT WITH NO ETA

Upgrade your failure-prone PCV breather hose with the high-performance, reliable 034Motorsport PCV Breather Hose, engineered for enhanced durability and long-lasting performance. The 034Motorsport PCV Breather Hose isn't just an upgrade for tuned vehicles - it's also a critical safety enhancement for all EA839-equipped vehicles.

The PCV breather hose on the EA839 relies on a pair of internal check valves to switch between ventilation pathways and prevent the loss of crankcase vacuum or entrance of boost pressure to the engine crankcase; however, these factory components are prone to premature failure. Once these check valves fail, they can no longer regulate crankcase pressure properly, causing the crankcase to pressurize and potentially allowing hot oil to escape that can lead to serious engine damage, including the risk of fire. This failure occurred to a development vehicle in Ashes to Asphalt, documenting the absolute worst case scenario of when the PCV system can fail. This failure can occur on bone-stock vehicles or vehicles tuned with Stage 1, 2, or 3 power levels. The 034Motorsport PCV Breather Hose is designed to offer reliable crankcase ventilation for the EA839 V6 at all power levels.

The 034Motorsport PCV Breather Hose fixes these critical safety issues, allowing the PCV system to operate flawlessly at all power levels for years to come.

Upgrade your factory corrugated plastic, failure-prone PCV breather hose with the high-performance, reliable 034Motorsport PCV Breather Hose, engineered for enhanced durability and long-lasting performance.

The PCV, or Positive Crankcase Ventilation system, on the EA839 is located on bank 2 of the engine (The right side of the engine). It is designed to ventilate the engine's positive crankcase pressure through the breather hose into the intake tract or charge air system. The breather hose plays an integral role in this ventilation system, which uses two check valves to control the flow of crankcase pressure.

How Does the PCV System Operate?

The Positive Crankcase Ventilation System on the EA839 works to remove excess pressure from the crankcase system and relies on the vacuum from the engine's intake system to operate properly. At idle or cruising while not in boost, the engine's charge air system operates under vacuum, drawing air in continuously. During this state, the PCV system utilizes this vacuum to release crankcase pressure into the charge air system through the connection just after the throttle body.

However, when the vehicle is under boost (during acceleration), this connection becomes pressurized, meaning it can no longer provide a vacuum source for crankcase ventilation. When this happens, a check valve in the breather hose closes off this connection, preventing boost pressure from entering the crankcase. At this point, the breather hose is able to draw vacuum from the turbo inlet connection, as this creates vacuum through a siphoning effect as the turbocharger draws air in through the intake.

Whether you are sitting at a stoplight or romping on a backroad, a properly operating PCV system is crucial for maintaining the engine's performance and preventing harmful pressure buildup.

Why is the OE PCV System Insufficient?

The check valves within the factory breather hose are an integral component of ensuring correct operation. However, since these check valves deal with the high temperatures of an engine bay and the transition between vacuum and boost pressure, they are susceptible to premature failure. When they fail, excess pressure can enter the crankcase, causing it to operate under conditions it was not designed for. In fact it's likely these are the same as what Audi uses on naturally aspirated engines, which makes them not up to the task of dealing with pressures associated with turbocharged engines.

As the crankcase of the engine is not designed to operate under pressure, it typically will find the path of least resistance to release this excess pressure. The seals and components inside your engine, which are designed to operate under vacuum, aren't built to handle this excess pressure. In some cases, the path of least resistance is unfortunately the oil cap, which can loosen and expel hot oil into the engine bay, potentially causing a fire.

Audi issued a TSB (Technical Service Bulletin) concerning this failure of the PCV Breather Hose as of 2020, though in our testing 034Motorsport has concluded that even the newest variant of breather hose is susceptible to failure.

Some other solutions on the market neglect the importance of maintaining adequate vacuum pressure from the charge air system and intake tract to ensure proper operation of the PCV system. Because the PCV system relies on these two separate vacuum sources under normal operation, removing one would prevent the crankcase ventilation system from functioning properly.

When these solutions remove the intake tract as a vacuum source, it disrupts the PCV system's ability to vent crankcase pressure at idle or in a cruising state while not in boost. Because the crankcase no longer has sufficient vacuum pressure, seals that are designed to operate with this vacuum pressure can fail prematurely. This lack of vacuum pressure can also lead to the potential of pressurization of the crankcase system and engine damage.

Additionally, many aftermarket solutions have check valves that do not provide sufficient flow to accommodate the boost levels of Stage 3 equipped vehicles. These check valves are too small and this inefficiency can cause restrictions, resulting in reduced flow from the crankcase, causing crankcase pressure to build up.

During the development of the 034Motorsport Stage 3 Dynamic+ tuning suite, the development B9 Audi S4 experienced an unfortunate OEM PCV breather hose failure.

This failure caused oil to be expelled through the oil cap and onto the hot turbocharger, immediately causing an engine oil fire. This failure was documented in our video Ashes to Asphalt, documenting the extent of the damage and how 034Motorsport was able to make the most out of the situation.

Because of this failure, it made engineering a proper solution that was able to withstand the harsh engine bay temperatures and elevated boost levels of utmost priority for 034Motorsport Engineers.

What is The Fix?

034Motorsport began by benchmarking the factory PCV system for flow capacity and other check valves on the market. Due to this, we opted to engineer and develop our own proprietary check valves that offer fantastic restrictionless-flow capability when open, and create a strong seal when closed, capable of holding over 40+ PSI of pressure and dealing with the high temperatures this system is subject to. These check valves utilize a durable synthetic rubber diaphragm that offers superior high heat and chemical resistance.

034Motorsport engineers designed the 034Motorsport PCV Hose to be used with the OEM Factory Air Oil Separator, as we found during testing that this unit provides excellent crankcase pressure control and is capable of supporting the flow needed at Stock through Stage 3 power levels without failure.

The 034Motorsport Check Valves are housed in a high-flow 4-ply reinforced silicone hose, specially designed to not collapse or inflate under vacuum or boost pressure. These silicone hoses are molded to allow for the factory engine cover to be utilized with the 034Motorsport PCV Breather System installed.

The 034Motorsport PCV Breather Hose uses OE-style multi-use connections, which allow for easy installation and removal when servicing your turbo inlet.

The OEM breather hose includes a new turbo inlet system as well, increasing the cost of this failure-prone component. whereas with the 034Motorsport PCV Breather System installed, there is no need for excessively costly OEM replacement components, as the 034Motorsport Breather Hose is engineered to last the lifetime of your vehicle.

The result is the 034Motorsport PCV Breather Hose, which isn't just an upgrade for performance enthusiasts€”it's a critical safety enhancement for all EA839-equipped vehicles. It has been extensively tested on several 034Motorsport development vehicles for upwards of 2 years at varying power levels to ensure its performance and reliability, whereas the OEM breather hose can fail in as little as 3 months! The 034Motorsport PCV Breather Hose is suitable for all vehicles including those that are bone stock or upgraded with Dynamic+ Stage 1, 2, or 3 tuning!

Features:

  • Direct Replacement of the Failure Prone OE PCV Hose
  • Ensures High Flow Crankcase Ventilation to Prevent Crankcase Pressurization
  • Eliminates Potential Boost Leak at OE Plastic Check Valve Housing
  • Supports Boost Pressures to 40+ PSI
  • Compatible with OEM and Upgraded Turbocharger Inlets
  • CNC-Machined, Billet Aluminium Check Valve Body (Black Anodized), with a Heat and Chemical Resistant, Durable Rubber Diaphragm
  • 4-Ply, Reinforced, Silicone Hose
  • Retains Factory Engine Cover
  • Simple Installation

Fitment:

* 034-101-3108 is for B9 3.0T engines such as S4/S5/SQ5 does not fit the 2.9TT which is 034-101-3109.

Make Model Years Chassis Engine Note
Audi A6 2019-Present C8 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi A7 2019-Present C8 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi allroad 2019-Present C8 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi S4 2017-Present B9/B9.5 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi S5 2017-Present B9/B9.5 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi SQ5 2017-Present B9/B9.5 3.0 TFSI Select: B9/B9.5/C8 3.0T Engines
Audi S6 2019-Present C8 2.9 TFSI Select: B9/B9.5/C8 2.9T Engines    
Audi S7 2019-Present C8 2.9 TFSI Select: B9/B9.5/C8 2.9T Engines    
Audi RS4 2018-Present B9/B9.5 2.9 TFSI Select: B9/B9.5/C8 2.9T Engines    
Audi RS5 2018-Present B9/B9.5 2.9 TFSI Select: B9/B9.5/C8 2.9T Engines    

 

The installation of your 034Motorsport PCV Breather Hose, EA839 2.9T/3.0T is a straighforward process that should take approximately 1 hour or less to complete. You can access our detailed installation guide by clicking the link below.

Download the 034Motorsport PCV Breather Hose, EA839 2.9T/3.0T Install Guide

Recommended product: Audi B9 S4 ECU Tuning
Recommended product: Audi B9 S5 ECU Tuning

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
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  • Delivery to the USA:
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 69785357549

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D
Dale Kim
Lexington, US
★★★★★ 5
Soft and comfortable cooling pillowcase that gets the job done!
Color: White, Size: Queen, Color: White, Size: Queen
I got this quilted bamboo pillow protector (queen size) because I wanted a cleaner, cooler layer between my pillow and pillowcase since I’m always hot. This has been a great solution for that. The fabric feels soft and smooth, and it doesn’t make that crinkly noise some cooling pillowcases do. I’m a warm sleeper and the “cooling” aspect feels more like breathable than icy-cold, but it definitely sleeps more comfortably than the thick polyester protectors I’ve used in the past. The light quilting adds a little cushion without making my pillow feel bulky or changing the loft much. I like the fact that if you use a memory foam fill pillow you can add or remove some of the filling to make the pillow as firm or mushy as you want. This is especially helpful for people that are side sleepers vs people that need more neck support. The zipper is a big plus. Just be careful when zipping it open and closed as these are usually the first point of failure for pillowcases in my experience. It closes fully and keeps the protector snug so it doesn’t shift around inside the pillowcase, and it gives me peace of mind for sweat / oils and everyday wear. I’ve washed it and it came out fine with no weird shrinking, and the stitching still looks clean. For the price, it feels like good value if you’re trying to extend the life of a nicer pillow while keeping the sleep surface soft and breathable. It’s one of those small upgrades you don’t think about much once it’s on, which is kind of the point. It just works and helps me sleep more comfortably.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 1, 2026
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Codescriber
Draper, US
★★★★★ 5
Soft and cooling
Color: White, Size: King, Color: White, Size: King
This pillow cover is great! Well made. Not too thin. Fits my queen pillow like a glove. Came out of the washing machine still looking brand new, with no zipper issues, which can happen with lower quality covers. Zero complaints.
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Reviewed in the United States on January 21, 2026
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Anon-A-Mouse Reviewer
Lexington, US
★★★★★ 5
Soft, Cooling Pillowcase That Smooths Out Chunky Filling
Color: White, Size: King, Color: White, Size: King
I accidentally ordered the king size instead of queen, but it still fits my shredded latex foam pillow fairly well and feels comfortable. The pillow has small but chunky latex shreds, and the added foam layer in this pillowcase not only smooths out those chunks but also adds a bit of extra thick comfort, making the pillow feel more uniform. ​ It seems to help with temperature regulation—if anything, it’s subtly cooler or at least not any warmer than my previous pillowcase. I’ve washed it twice so far, and it shows no wear and seems well built, so it should hold up over time and seems totally washable. Overall, it’s a very functional item, and compared with similar products, the value seems reasonable; I’m happy with the purchase and just wish I had ordered the right size. ​
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Reviewed in the United States on December 23, 2025
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Dr. R
New York, US
★★★★★ 4
Good quality cover
Color: White, Size: Queen, Color: White, Size: Queen
First, this pillow cover arrived in a plastic bag (see 4th photo), not a box as the photos online show. Although that does not matter to me, it may matter to other people such as those who intend to give this as a gift. One of the photos I included shows the fabric makeup which is mostly polyester and memory foam with the outer cover having “40% Bamboo Rayon.” It seems like an overstatement to me to market this product as a “quilted bamboo pillow cover” where there’s very little, if any, actual bamboo in it. If you have read up on what “bamboo rayon” actually is, you’ll understand. The material make up aside, the cover is soft and puffier than a cotton pillowcase. Bamboo rayon does have qualities that allow airflow for a cooling type of effect. It washes very nicely. As for the size of the pillar cover, I have tried several pillows inside this case, and the case is at least 2 inches longer than every standard pillow I own (See second photo). Pillowcases with a zipper generally are more fitted in every dimension. This pillow cover fits in all dimensions, except for it is longer than necessary. Not a horrible thing, but worth mentioning. The sewing of this product is good. It has a standard plastic zipper. There’s piping around the entire seam area for touch of class. The gray piping on mine matches the quilting. This is not quilting of the standard sense where threads go through to the other side. It is more of a faux quilting, which you can that on the inside in the photo with the tag. Overall, it seems to be a good product especially for people who sweat when they sleep. Quilted Bamboo Pillow Cover Collection – Cooling Pillow Protector with Zipper – Soft, Breathable & Washable Fabric (White, Queen) $19.99 at the time of this review
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Reviewed in the United States on November 7, 2025
J
Jailyn
Pawtucket, US
★★★★★ 5
Very easy and convenient
Color: White, Size: Queen
Absolutely in love with this pillow case. I have a tendency to let the kids on the bed with snacks and it’s helpful to just be able to take the case off and put it in the washer when it’s dirty
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