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Catalyst / Bypass
Securely seal an unused oxygen sensor port with this OE Match Blanking Plug for Oxygen Sensor Hole. Designed for compatible exhaust applications, this plug is used when an oxygen (lambda) sensor mounting hole is present but a sensor is not required for the particular vehicle, exhaust configuration, testing setup or application.
M 18 x 1,5 x 18
23mm in length
Oxygen sensor ports are threaded openings in the exhaust system that normally accommodate a lambda sensor. When the port is not being used, it must be properly sealed. Leaving the opening exposed can allow hot exhaust gases to escape and may permit moisture and contamination to enter the exhaust system.
What This Product Does:
- Seals an unused oxygen or lambda sensor mounting hole.
- Prevents exhaust gases escaping through an unused sensor port.
- Helps maintain the integrity of the exhaust system.
- Protects the threaded sensor opening from dirt and contamination.
- Helps reduce moisture entering through an unused port.
- Allows an exhaust component with an oxygen sensor boss to be used where a sensor is not required.
- Provides a removable solution if an oxygen sensor is required later.
- Replaces a missing, damaged or corroded blanking plug.
- Provides an OE-style solution for compatible exhaust applications.
Symptoms Of Wear Or Failure:
- Exhaust gases leaking around the plug.
- A ticking or blowing noise from the oxygen sensor port.
- Black soot deposits around the plug or threaded opening.
- A strong exhaust smell near the affected area.
- The plug has become loose.
- Visible corrosion or deterioration.
- Damaged or stripped plug threads.
- A plug that can no longer be securely tightened.
- The original blanking plug is missing.
- An oxygen sensor has been removed and the port remains open.
- Heat or exhaust staining around the sensor boss.
Why Replacement Matters:
- An unused oxygen sensor hole should never be left open during normal engine operation. Exhaust gases are extremely hot and can escape through the opening at high velocity, potentially damaging nearby components and creating excessive noise.
- An exhaust leak can also affect the correct operation of the exhaust system. Depending on the location of the unused port and the vehicle's configuration, unwanted air entering the exhaust may also interfere with exhaust-gas measurements or diagnostic testing.
- The threaded sensor boss itself can deteriorate if left exposed. Dirt, moisture and corrosion may damage the threads, making installation of a future oxygen sensor more difficult or requiring repair of the sensor mounting point.
- A loose or damaged plug can produce similar problems. Soot deposits around the port are often an indication that combustion gases are escaping past the sealing surface or threads.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
333660211
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50

Fits:
Porsche 911 2.7L 1975-89
Porsche 930 3.0L, 3.3L Turbo 1975-89
Please note: These sport cats will make your car sound louder than with stock cats. If you have ,or intend to install sport silencers, you may find the car is a bit loo loud. We recommend to use one sport exhaust component if you are concerned about decibel levels.
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
911PO92100S
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Exhaust Catalytic Converters & Bypass Pipes – Performance, Efficiency & Flow Control
The catalytic converter plays a crucial role in your Porsche’s exhaust system, reducing harmful emissions while maintaining optimal exhaust flow. Positioned between the exhaust manifold and silencer, it converts toxic gases such as carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful emissions before they exit the tailpipe.
At Design911, we offer a complete range of catalytic converters and bypass pipes for Porsche vehicles. Our manufacturer-quality converters ensure reliable emission control and long-term performance, while our bypass options are designed for track or performance use, optimising exhaust flow for maximum power and throttle response.
Whether you’re maintaining your Porsche to meet emissions standards or upgrading for improved exhaust performance, our selection includes both direct-fit converters and performance bypass kits built from high-grade stainless steel for strength, corrosion resistance, and durability.
What Do Catalytic Converters & Bypass Pipes Do?
A catalytic converter uses a fine mesh of precious metals to trigger chemical reactions that break down pollutants. The bypass alternative eliminates restriction in the exhaust flow, improving performance in non-emissions-controlled environments such as track driving.
Core Functions:
- Converts
toxic exhaust gases into environmentally friendly emissions.
- Maintains
exhaust back pressure for engine efficiency.
- Reduces harmful NOx, CO, and HC emissions.
- Supports smoother engine performance and throttle control.
- Bypass versions enhance exhaust flow and improve power output for track cars.
Upgrading to a performance-grade system ensures your Porsche continues to meet emission requirements — or achieves greater flow and responsiveness for motorsport applications.
Why Do Catalytic Converters Fail?
Catalytic converters are exposed to extreme heat, unburnt fuel, and contaminants — all of which can degrade their performance over time.
Common Causes of Failure Include:
- Carbon
or oil buildup blocking the internal honeycomb.
- Thermal
damage from overheating or rich fuel mixtures.
- Physical
damage from road debris or misfiring engines.
- Corrosion
due to moisture and exhaust condensation.
- Age-related wear reducing catalytic efficiency.
A failing converter can cause reduced engine power, poor
fuel economy, rattling sounds, or a check-engine light. Replacing it
restores emissions compliance, performance, and exhaust efficiency.
Why Replace or Upgrade
with Precision-Engineered Components?
Replacing a failing converter or upgrading to a bypass pipe ensures your Porsche maintains peak performance and reliability.
Key Benefits:
- Restores optimal emissions performance and efficiency.
- Improves exhaust flow and throttle response.
- Reduces engine stress and fuel consumption.
- Durable stainless-steel construction for longevity.
- Direct-fit
compatibility for Porsche 911, Cayman, Boxster, Panamera, Macan
and more.
- Performance bypass options available for track and tuning applications.
Whether you want emissions compliance or maximum flow for competition use, our parts deliver reliability, precision, and performance.
Highlights:
- Direct-fit catalytic converters and bypass pipes for Porsche models.
- Precision-engineered for optimal flow and reduced emissions.
- Built from heat-resistant stainless steel for durability.
- Bypass pipes for performance tuning and track applications.
- Restores power, efficiency, and exhaust sound balance.
- Available for classic and modern Porsche vehicles.