Audi S5 Catalytic Converters: Complete Guide

Audi S5 Catalytic Converters: The Audi S5 is a high-performance coupe known for its powerful engine and luxurious features. Introduced in 2007, the S5 has become popular among car enthusiasts. Like many performance vehicles, the Audi S5 has multiple catalytic converters to help reduce emissions and ensure compliance with environmental regulations. These high-quality catalytic converters play a crucial role in the S5’s exhaust system, effectively converting harmful gases into less harmful substances. With its sleek design and exceptional driving performance, the Audi S5 offers a thrilling driving experience while prioritizing environmental responsibility.

Direct-fit replacement Audi S5 Catalytic Converters are available from aftermarket brands like Autozone catalytic converter, Bosal, Eastern Catalytic, and Walker. Proper inlet/outlet dimensions and flange style must match the original converters. Audi S5 Catalytic Converters sold in California must be CARB-compliant.

Specific Details on the Audi S5 Catalytic Converters

Common Signs For Bad or Clogged Audi S5 Catalytic Converters

  • Check engine light: Warning light for the engine. Checking the engine warning light is a valuable way to tell whether or not there is a problem with the emissions system in your vehicle. A professional mechanic must check out your car immediately if the “check engine” light turns on in your dashboard.
  • Reduced fuel economy: Your car’s fuel consumption efficiency may suffer if Audi S5 Catalytic Converters malfunctions since it cannot convert dangerous exhaust gases into less harmful gases at the same efficiency level.
  • Engine Misfires: If Audi S5 Catalytic Converters aren’t working properly, it could cause engine misfires. This is because the catalytic converter cannot reduce the quantity of carbon monoxide in the exhaust fumes.
  • Increased Emissions: A catalytic converter in your car that isn’t working properly may cause increased emissions. This is due to the inability of the catalytic converter to transform hazardous exhaust gases into gases that are less detrimental to the environment.
  • Excessive Exhaust Noise: Noise from the exhaust system that is excessive. A catalytic converter that is not working fine can create excessive noise from the exhaust system. This is due to the catalytic converter’s inability to significantly reduce the quantity of noise produced by the exhaust gases.
  • Dark Exhaust Smoke: An exhaust with a dark color is a symptom of a clogged catalytic converter, which can also generate this exhaust color. This is due to the inability of the catalytic converter to transform hazardous exhaust gases into gases that are less detrimental to the environment.

Troubleshooting Tips for Audi S5 Catalytic Converters:

  • Check for P0420/P0430 codes pointing to converter failure using an OBD2 scanner.
  • Listen for rattling noises from the exhaust, indicating internal damage.
  • Inspect oxygen sensor performance upstream and downstream of converters.
  • Look for reduced performance, increased fuel usage, and rotten egg smells.
  • Use Catalytic Cleaner for catalytic converting cleaning

Installation Tips:

  • Always replace the exhaust inlet/outlet gaskets when installing the new Audi S5 Catalytic Converters. High-temperature silicone sealant can also be used to seal connections.
  • The inlet/outlet pipe diameter is 2.5″. Ensure the replacement converters have the proper 2.5″ inlet and outlet ports.
  • When secured to the manifolds, use a torque wrench to tighten the converter mounting nuts/bolts to the proper spec of 22-27 ft-lbs.
  • Carefully detach and reattach the oxygen sensors from the original converters to the new ones in their same locations.
  • Clear any check engine codes with a scan tool after installing the new Audi S5 Catalytic Converters. This will reset fuel trim parameters and monitor operation.

Read More: Audi SQ5 Catalytic Converters: Everything About It

Tips for Cleaning Audi S5 Catalytic Converters:

  • Use a catalytic converter cleaner. Products like Catalytic Converter Cleaners can help break down and remove contaminants and deposits inside the catalytic converter. Follow the directions on the product.
  • Flush the catalytic converter. You can do this by adding the catalytic converter cleaner to your gas tank when filling up, and then driving the car for 30-60 minutes on the highway. The high speeds and engine heat will help circulate the cleaner through the catalytic converter to remove deposits.
  • Use a shop vac to vacuum out loose debris. Disconnect the oxygen sensor and carefully insert the vacuum hose into the catalytic converter inlet. Be careful not to damage the honeycomb structure inside.
  • You may need to remove the catalytic converter and soak it in a solvent-based or acid-based cleaner for heavy carbon deposits. Make sure to thoroughly rinse and dry it before reinstalling.
  • Avoid using engine degreasers or harsh chemicals that could damage the catalyst material inside the converter. Stick to products specifically made for catalytic converter cleaning.
  • Be gentle in your cleaning methods to avoid damaging the converter. Over-cleaning or using too much pressure can harm the internal structure.
  • Consider having a professional mechanic do the cleaning if you’re uncomfortable with the process. They’ll have the proper tools and skills.

Read More: Audi S8 Catalytic Converters: A Comprehensive Guide

Some Tips For Properly Washing Audi S5 Catalytic Converters

  • Use a degreaser or catalytic converter cleaner. Spray it directly onto the exterior casing of the Catalytic Converters and let it soak for 5-10 minutes. This will help break down oil, grease, and carbon deposits. Avoid getting cleaner inside the converter.
  • Rinse the converter thoroughly with a garden hose or pressure washer. The high-pressure water will help blast away loosened contaminants.
  • Use a soft brush or rag to scrub the converter’s outside for stubborn deposits. Avoid abrasive pads or brushes that could damage the metal casing.
  • Ensure you thoroughly flush out any catalytic converter cleaner you use with plenty of water. Leftover chemical residue can damage the catalyst over time.
  • Dry the Audi S5 Catalytic Converters fully after washing, using compressed air if available. Moisture left inside can also degrade the catalyst. Let the converter idle for 10-15 minutes to help evaporate any moisture.
  • Avoid using harsh chemicals like engine degreasers directly on the converter, as they can wash away the catalyst material and degrade performance over time.
  • Do not attempt to wash inside the converter or scrape at the honeycomb – this will destroy it. Only clean the outer casing.
  • Consider having a professional detail shop wash the catalytic converter if you don’t have the proper tools. They can properly clean it without damage.

The key is to be gentle and use only Catalytic Converter-approved cleaners. Thorough rinsing is important. Avoid excess moisture inside the converter.

Life Of Audi S5 Catalytic Converters

  • Under normal driving conditions, the OEM Audi S5 Catalytic Converters can average 120,000-150,000 miles.
  • The converters have an 8-year/80,000-mile federal emissions warranty. California emissions models have a 15-year/150,000-mile warranty.
  • Driving style has a big impact. Many short trips and cold starts can foul the converters faster than longer highway driving.
  • Poor engine maintenance, like oil leaks, bad spark plugs, or issues causing misfires, will degrade the converters quickly.
  • Contaminants like oil, coolant, or fuel getting into the exhaust can coat and damage the converter’s internals.
  • The upstream converter near the engine tends to fail sooner due to more heat cycling. The downstream one often lasts longer.
  • The efficiency declines if the Check Engine light comes on for a catalytic converter code. Replacement is recommended.
  • Periodic visual inspections of the converters can help spot potential issues early. Signs include blocked flow, rattling, and visible damage.
  • Aftermarket replacement converters typically have a shorter 50,000-80,000-mile lifespan. OEM parts tend to last longer.

How To Replace Audi S5 Catalytic Converters


It uses multiple catalytic converters, one on each exhaust manifold bank. The new converters must be bolted into the original mounting positions for proper exhaust flow.

Exhaust Seals:

When installing the Audi S5 Catalytic Converters, use new gaskets to seal the inlet and outlet flanges. Apply high-temperature silicone sealant as well to prevent leaks.

Oxygen Sensors:

Carefully detach and reattach the oxygen sensors from the old converters to the new ones. Position the upstream and downstream sensors properly.

Inspect Other Components:

Inspect the exhaust manifolds, mounts, and pipes when replacing the Audi S5 Catalytic Converters. Look for any leaks or damage that needs addressing.

Post-Installation Check:

After installing the new Audi S5 Catalytic Converters, clear any codes and road-test the vehicle. Verify the catalyst efficiency monitors are set to ready and that no check engine lights return.

Top FAQs Related to Audi S5 Catalytic Converters

What is a catalytic converter in an Audi S5, and what does it do?

A catalytic converter is a vital emissions control device in an Audi S5 that helps reduce harmful exhaust gases by converting them into less harmful substances.

How often should I replace the catalytic converter in my Audi S5?

Catalytic converters typically last for several years. However, they may need replacement if they become damaged or fail to perform efficiently.

What are the signs of a failing catalytic converter in my Audi S5?

Signs include reduced engine performance, increased emissions, a noticeable decrease in fuel efficiency, and warning lights like the “Check Engine” light.

Can I clean or repair a damaged catalytic converter in my Audi S5?

In most cases, catalytic converters cannot be effectively cleaned or repaired. Replacement is often the best solution for a damaged converter.

How much does replacing a catalytic converter in an Audi S5 cost?

The replacement cost can vary based on the model year and location. Still, it typically ranges from a few hundred to over a thousand dollars.

Is replacing the catalytic converter in my Audi S5 with an aftermarket one legal?

In many regions, replacing the catalytic converter with an aftermarket one is legal as long as it meets emissions standards. Check local regulations to be sure.

Can I install a high-performance catalytic converter in my Audi S5 for better engine performance?

Some high-performance catalytic converters can improve engine performance but ensure emissions are compliant to avoid legal issues.

What can cause premature failure of a catalytic converter in an Audi S5?

Factors like engine misfires, oil or coolant leaks, and excessive fuel additives can contribute to premature catalytic converter failure.

How do I maintain Audi S5’s catalytic converter to extend its lifespan?

Regular maintenance, Fixing engine issues promptly, and using high-quality fuel can help prolong the life of your catalytic converter.

What is the warranty coverage for the catalytic converter in my Audi S5?

Warranty coverage for the catalytic converter can vary by model year and location. Consult your Audi dealership or refer to your owner’s manual for specific warranty information.

I am Nicolas, an automobile engineer with over 5 years of experience in exhaust systems and catalytic converters. I am passionate about learning and understanding how things work, and I am always looking for new ways to improve the performance and efficiency of automotive exhaust systems.

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