Subaru XT Catalytic Converters Ultimate Guide

Subaru XT Catalytic Converters: The Subaru XT, produced from 1985 to 1991, was a stylish and sporty coupe. It also featured a 4-cylinder engine and a single catalytic converter. The XT was known for its unique design, distinctive wedge-shaped body, and advanced features. The Subaru XT offered a fun and exhilarating driving experience with its turbocharged engine options and all-wheel drive capabilities. Although no longer in production, the XT remains a beloved classic among Subaru enthusiasts.

Direct-fit replacement Subaru XT 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. Subaru XT Catalytic Converters sold in California must be CARB-compliant.

Specific Details on the Subaru XT Catalytic Converters

Common Signs For Bad or Clogged Subaru XT 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 the Subaru XT Catalytic Converters malfunctions since it cannot convert dangerous exhaust gases into less harmful gases at the same efficiency level.
  • Engine Misfires: If Subaru XT Catalytic Converters aren’t working correctly, 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 Subaru XT 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 a Catalytic Cleaner for catalytic converting cleaning.

Installation Tips:

  • Always replace the exhaust inlet/outlet gaskets when installing the new Subaru XT 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 Subaru XT Catalytic Converters. This will reset fuel trim parameters and monitor operation.

Read More: Subaru XV Crosstrek Catalytic Converters Ultimate Guide

Tips for Cleaning Subaru XT 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 made explicitly 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: Subaru WRX STI Catalytic Converters Guide

Some Tips For Properly Washing Subaru XT 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 bushes 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 Subaru XT Catalytic Converters thoroughly 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 water.
  • 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 need 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 essential. Avoid excess moisture inside the converter.

Life Of Subaru XT Catalytic Converters

  • Under normal driving conditions, the OEM Subaru XT 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 significant impact. Many short trips and cold starts can foul the converters faster than more extended 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 Subaru XT 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 Subaru XT 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 Subaru XT Catalytic Converters. Look for any leaks or damage that needs addressing.

Post-Installation Check:

After installing the new Subaru XT 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.

FAQs about Subaru XT Catalytic Converters

What is a catalytic converter in a Subaru XT, and what does it do?

A catalytic converter in a Subaru XT is an emissions control device that helps reduce harmful pollutants like carbon monoxide, nitrogen oxides, and hydrocarbons from the exhaust gases.

How long does a Subaru XT catalytic converter typically last? 

The lifespan of a Subaru XT catalytic converter can vary, but on average, it can last between 100,000 and 150,000 miles. Factors like driving conditions and maintenance can influence its longevity.

What are the symptoms of a clogged catalytic converter in a Subaru XT? 

Symptoms of a clogged catalytic converter may include reduced engine performance, decreased fuel efficiency, and the illumination of the “Check Engine” light on your Subaru XT’s dashboard.

Can a clogged catalytic converter be cleaned, or is replacement the only option? 

While some cleaning products are available, they may only sometimes be practical for severely clogged catalytic converters. Replacement is often the best course of action in such cases.

What is the approximate cost of replacing a Subaru XT catalytic converter? 

The price of a replacement Subaru XT catalytic converter can vary based on factors like the model year, location, and whether you choose an OEM or aftermarket part. Prices can range from $200 to $800 or more.

Is it legal to scrap a Subaru XT catalytic converter?

Scraping a Subaru XT catalytic converter is legal, but regulations regarding the sale and disposal of catalytic converters may vary by location. Be sure to check local laws and regulations.

What is the scrap price for a Subaru XT catalytic converter?

The scrap price for a Subaru XT catalytic converter can fluctuate based on factors like the type of precious metals used inside it. It’s advisable to check with local scrap yards or recycling centers for current rates.

Are there any aftermarket catalytic converters available for Subaru XT models? 

Yes, there are aftermarket catalytic converters designed for Subaru XT models. They can offer cost-effective alternatives to OEM replacements, but choosing high-quality options is essential.

How can I extend the life of my Subaru XT catalytic converter? 

To extend the life of your Subaru XT catalytic converter, follow a regular maintenance schedule, avoid driving with a misfiring engine, and use high-quality fuel to reduce carbon buildup.

What is the best cleaner for Subaru XT catalytic converters? 

Several catalytic converter cleaners are available, but choosing a product specifically designed for cleaning catalytic converters is essential. Always follow the manufacturer’s instructions for the best results.

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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