New Catalytic Converter Smell: Proven Causes & Measures!

The new catalytic converter smell is unmistakable and can be a bit overwhelming. This pungent chemical odor can often be described as a combination of burning rubber and sulfur.

Many people find the smell unpleasant, which can linger in the air for days after installation. But why does it smell so strong and not disappear? 

Presumably, the reaction occurring when these chemicals interact creates multiple by-products, including carbon monoxide and nitrogen oxides, and an unwanted smell.

To analyze the root causes and viable measures in-depth, scroll down!

New Catalytic Converter Smell: What Are The Root Causes?

new catalytic converter smell
Why Is New Catalytic Converter Smell

Why does my car smell like carbon monoxide or other unpleasant odors after a catalytic converter change? 

There are 5 culprits for normal and bad smells of the new catalytic converter, including the oil coating, exhaust putty, label burning, exhaust fumes, and sulfuric scent.

Normal New Catalytic Converter Odors

What does a bad catalytic converter smell like? When first installed, catalytic converters often emit a couple of distinct odors.

Many weird odors can disappear after an hour on the road, yet some can linger for days.

Oil Coating

All brand-new exhaust parts, including catalytic converters, are coated in oil to avoid corrosion when kept in a shelf-space environment.

Usually, after a few hours, the exhaust coating burns off and leaves an off-putting odor.

Exhaust Putty 

The catalytic converter is a standard component of every exhaust system replacement. The exhaust gasket supports sealing thanks to a sealing putty.

Specific exhaust/sealant pastes can take up to 24 hours to cure and give off an unpleasant odor for a short time afterward.

Label Burning

The labels affixed to catalytic converters with supplier part numbers are typically not removed by technicians before installation, though they ought to.

The labels vanish once the catalytic converter is heated up, leaving a smoke with a catalytic converter burning smell. Lucky you, it only exists for a few days.

Bad New Catalytic Converter Odors

Does a bad catalytic converter smell? Yes, absolutely. If this is the case, you can notice the exhaust fumes or new catalytic converter smells like rotten eggs.

Unpleasant Exhaust Fumes Smell

The unsealed pinhole leaks between the joints and welds make the exhaust emissions can’t escape as normal.

The minor leak fails to come with an aggressive sound, as expected, leading to a strong clogged catalytic converter smell.

Sulphuric Odors

Does a new catalytic converter smell? Here is another answer to this question. Brand-new components often convert a tiny amount of sulfur.

It generates a hefty eggy odor once your catalytic converter fails, as sulfur isn’t converted correctly.

Thus, it’s a sure sign of a lousy converter.

So, how to fix catalytic converter smell? The best way for a catalytic converter smell fix to eliminate the rotten-egg scent is to alter the broken component producing it.

The irritating scent should go away once you apply it this way.

You must adopt the right catalytic converter removal tools to uninstall the current converter before mounting a new one.

How Catalytic Converters Work And When They Need Replacing

A honeycomb-shaped construction with a palladium and platinum coating houses a catalytic converter.

These two help the chemical inside convert dangerous exhaust gasses into less dangerous ones like carbon monoxide, hydrocarbon, and nitrogen oxide.

These pollutants can ruin your health and the air quality.

The larger the surface area is, the more gasses can be transformed into less toxic fumes.

Similar to how your vehicle’s oil and air filters must be updated occasionally. Over time, converters can deteriorate and require replacement.

A converter’s lifespan can be over 100,000 miles under typical circumstances.

The converters in your vehicle may become ruined after a few thousand miles if the engine has a technical issue.

The rust can lead to a broken converter. Thus, this section requires periodic maintenance.

When Will New Catalytic Converter Odor Go Away?

how to fix catalytic converter smell
New Catalytic Converter Smell Go Away

Do new catalytic converters smell? Yes, you’ve got the answer to this. But how long will it vanish?

It smells like oil, glue, and other chemicals are burning off or warming up as you install a brand-new catalytic converter.

Yet, the offensive smell may disappear within a few minutes, hours, or days, based on your driving style and frequency.

But, if the smell persists after installation over a few hundred miles or if it doesn’t go away, you might have further trouble calling for expert support.

For instance, the odor’s source could be a malfunctioning O2 sensor or clogged filters with excess oil.

What Should I Do After Installing A New Catalytic Converter?

To function properly, brand-new catalytic converters need to “break in.” Its internal materials could suffer if it isn’t adequately warmed up, resulting in an early component failure.

More than that, most catalytic converters are cracked at the technician’s shop, yet some buyers are not aware of this. So, check it sparingly before making a purchase.

The internal matting inside the converter holding the substrates will only properly expand or stay in place if the owner gives the car a good break-in.

Because of this, the internal parts start to jiggle and become loose or broken.

How To Break In A New Catalytic Converter?

You must first warm up your new catalytic converter to cushion the inside components and guard against early damage. Double-check after this step if needed.

The break-in procedures for a replacement catalytic converter are as follows:

  • Start the auto and do not hit the gas pedal.
  • Wait for the car to heat up, then idle.
  • Wait 5 mins or until the engine reaches operating temperature.
  • Then, apply the accelerator pedal to rev up to 2500 RPM.
  • Release your gas pedal after two mins of keeping power at 2500 RPM.
  • After the car has finished cooling down utterly, switch it off.

Your new converter is now heated and ready to go. Do not forgo the warm-up step, as stated. Your catalytic converter may get irreversibly harmed while you overlook the break-in step.

For more help or have any queries, consult the professional.

What Are Other Signs A New Catalytic Converter Has Failed?

smell catalytic converter
The Symptoms Of Bad Catalytic Converter

The catalytic converter’s interior temperature is much higher than its processing temperature if it burns red and turns blue after cooling.

This occurs since the engines may operate lean or richly; lambda (O2) sensors on either side of the catalytic converter influence the air-fuel mixture ratios. 

The engine control light typically flashes when an O2 sensor malfunctions, though. In other words, the catalyst will be irreparably damaged once its color changes.

Poor Engine Performance

The catalytic converter is part and parcel of the car’s exhaust system. Thus, it can severely impact driving performance once it gets wrong.

Blocked items can restrict the exhaust flow. On the other hand, a fractured or clogged converter could emit dangerous gas. After that, it will hamper the engine power, acceleration, and fuel efficiency.

Check Engine Light Comes On

Once your catalytic converter deteriorates, the check engine light can turn on. Track the gas level and converter’s efficiency in your exhaust using sensors.

Eggy Smells

As stated, a properly catalytic converter converts the odorless sulfur dioxide from the gasoline’s hydrogen sulfide while the vehicle operates.

But a malfunctioning one can end up with a sulfur-like rotten egg smell from the exhaust pipe.

Not to mention, you might also notice darker exhaust smoke coming out of the tailpipe in this case.

Fail Emissions Test

In some states, an emissions test must be completed. Your car won’t pass this examination with an improperly working catalytic converter.

Rattling Sound

Too-rich fuel combinations will harm the converter’s inside. Over time, aging also causes damage. Within components may disintegrate, creating a rattling noise

Once the catalytic converter begins degrading, you might hear these sounds underneath the car. The condition will get worse without a timely fix.


Can A New Catalytic Converter Get Bad Out Of The Box?

Yes. Despite rare, it does happen; a brand-new catalytic converter may have issues right out of its box.

When the odor remains after a few miles of driving or appears from within the car, take the auto back to the shop for a checkup.

Could You Clean The Catalytic Converter?

Yes. Catalytic converter cleaning is optional but possible. Should you choose to clean it, use a detergent specially designed for catalytic converters.

The lacquer thinner catalytic converter cleaner is a sound option in this case.

Also, never use harsh chemicals to keep the converter in working order. Overall, the schedule is not that hard for DIYers, yet you’d better have a mechanic do it all if you’re not confident.

Final Thoughts

By and large, it’s common to notice the new catalytic converter smell. 

Knowing why it occurs and what precautions to take to avoid potential health risks and enjoy the new equipment is momentous.

Hopefully, this post is all about what you need. Other car owners may also encounter such a situation someday. Share this post with them!

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