Your car’s catalytic converter effectively transforms harmful gases into less harmful
ones, but over time they accumulate within it and buildup can buildup inside its
filters, leading oxygen sensors to mix fuel with air incorrectly. A clogged or failing
catalytic converter could even allow fuel/air mixture issues!
When this occurs, an unpleasant rotten egg aroma may arise as a result of hydrogen
sulfide being converted to inodorous sulfur dioxide by the converter.
Rattling
If your new catalytic converter emits an unpleasant odor, take it back to the
mechanic who installed it immediately. This is normal; the scent comes from label
adhesive and sealant burning off in a process known as bedding in.
Rattling noises could also be an indicator that the catalytic converter is beginning to
malfunction, with metal parts inside of it vibrating against other exhaust
components like the muffler or pipe sections and creating noise that vibrates
through your vehicle’s speakers.
Fuel, coolant or oil that leaks in through leaks may clog the catalyst and slow
powertrain performance, creating that unpleasant rotten egg smell and slowing
powertrain performance.
The 02 sensor before and oxygen sensor after catalytic converter monitor your
engine for fuel mixture problems, if these sensors fail your engine may run too rich
which clogs your catalytic converter and makes it stink, activating your check
engine light as well as creating codes in its computer system.
Egg Smell
Many homeowners have experienced the infamous rotten egg sulfur smell from
leaving hard-boiled eggs too long on the stove, but it could also be an indicator of
something much worse. Hydrogen sulfide gas leaks into homes through pipes or
sewer systems and can accumulate within your living environment quickly if they
detect an outbreak in sulfide levels in your environment. A sudden appearance could
indicate a gas leak; any sudden change could indicate you need to contact either
your utility company or local fire department immediately for repairs.
An effective catalytic converter converts harmful gasoline emissions like hydrogen
sulfide into non-odourous sulfur dioxide emissions. If it becomes blocked, however,
car engines cannot burn fuel properly which may result in acceleration, performance
and gas efficiency issues for drivers.
Rotten egg smell can also be caused by a malfunctioning fuel pressure sensor, which
allows too rich of a fuel mixture and damages or clogs the catalytic converter. You
can resolve this problem by replacing the sensor.
Burning Sulfur
As part of its combustion process, your engine produces hydrogen sulfide; your
catalytic converter’s job is to neutralize this by turning it into odorless sulphur
dioxide – otherwise known as “rotten egg odor.” If not working effectively it could
start clogging and emitting that unpleasant rotten egg smell.
If the rotten egg smell persists, you should immediately visit a mechanic. Mechanical
issues could be at play here such as an improper fuel pressure sensor reading, worn
piston rings or valve seals, leaky head gasket or even an air filter clog which would
lead to catalytic converter issues.
At first, a newly installed catalytic converter may emit an unpleasant rotten egg
smell as it heats up and starts working correctly, however this should subside after
some minutes as long as its catalyst is functioning correctly. If lingering odor persists
after just minutes it could indicate failure or theft of your converter.
Burning Oil
A catalytic converter works to reduce emissions by transforming fuel into gases that
don’t harm the environment. This is accomplished through oxidizing chemicals found
in gasoline like sulfur dioxide (S02) into an odorless compound.
Catalytic converter failure may leave unburned fuel behind in the exhaust system
and produce an offensive smell similar to rotten eggs, along with blue smoke
coming out of your tailpipe and/or your check engine light illuminated.
New catalytic converters may emit an unpleasant odor upon first starting up due to
various reasons, including label adhesive burning off and sealant curing. If this smell
doesn’t subside within several minutes it could indicate that there is something
amiss with the unit.