If you reside in a state with stringent emission regulations, your car must pass
regular smog tests. Failing these exams could incur fines every time it’s time to renew its registration.
Un-working catalytic converters can cause your vehicle to fail smog testing by failing
to burn hydrocarbon gasses efficiently, prompting check engine light illumination or
fuel economy issues as well as audible rattling noises from beneath its bodywork.
Symptoms typically include poor fuel economy or even rattle-worthy sounds when
testing is attempted.
1. Clean the Intake
Catalytic converters are metal canisters at the end of your exhaust pipe that help
reduce emissions by converting harmful gasses to less toxic ones. When they fail,
their function cannot be performed effectively and you’ll fail your emissions test.
Problems can arise if too much unburned fuel enters the exhaust system through
misfiring spark plugs, damaged engine head gaskets or leaky valve seals, leading to
too much unburnt fuel entering and increasing operating temperatures of catalytic
converters, melting their internal components and creating partial blockages in their circuitry.
To resolve this, the best method is driving the vehicle in order to heat it up and burn
off any accumulated oil or fuel residue in its catalytic converter. A short trip around
the block or to a gas station may help clear away clogs; just be careful if working underneath your vehicle!
2. Clean the Exhaust
The catalytic converter serves as your car’s last line of defense against
environmental pollutants. Situated between engine and muffler, it converts harmful
emissions to more environmentally-friendly forms before exiting through exhaust
pipe. When blocked with carbon deposits or damaged, its performance will suffer
dramatically, rendering an emissions test impossible and compromising engine performance.
As soon as your converter becomes clogged, you should notice a decrease in
acceleration power during acceleration and uphill driving, darker exhaust smoke
than normal and possibly a burning smell coming from undercarriage.
If your catalytic converter is clogged, use these methods to clean it. Start by having
someone rev and hold the engine at a steady RPM; monitor whether vacuum
readings drop slightly before increasing to their previous threshold levels again.
3. Replace the Catalytic Converter
Your car’s catalytic converter is one of the key components for controlling emissions.
It helps lower carbon monoxide, hydrocarbons and nitrogen oxide emissions that
cause breathing ailments as well as environmental pollution.
Under your engine between the exhaust manifold and muffler lies a catalytic
converter, resembling a muffler but featuring rare metal catalysts to help gasses
pass through and reduce harmfulness. As time goes on however, your catalytic
converter may wear out, leading to failure during emissions testing.
As part of replacing a catalytic converter, the initial steps involve clearing away any
obstructions such as exhaust manifold pipes or oxygen sensors that block access to
it. Spray bolts and nuts with penetrating oil so they’re easier to unscrew. Once this
step is completed, carefully unbolt and install your new converter according to its
instructions – these should provide clear guidelines as to which way round is the proper way for installation.
4. Replace the Fuel Filter
Carbon buildup or other conditions that partially block the honeycomb design of a
catalytic converter can lead to engine issues for your customer, often leading them
to stop running effectively and potentially even cause it to stall altogether. When
this occurs, new catalytic converters could be necessary.
Assuming your engine runs properly, the combustion of gasoline and other fuels
reduces emissions from its exhaust system; however, harmful chemicals and gases
still escape through it into the environment.
A catalytic converter utilizes precious metals such as palladium, rhodium and
platinum to cause a chemical reaction which converts harmful gases into less
hazardous compounds.
Code P0420 indicates that the catalytic converter isn’t effectively converting harmful
gases to safer ones as expected, leading to overheating of engine components and
damage of other parts in exhaust system components, ultimately decreasing vehicle
performance and making emissions testing challenging.