Modern catalytic converters use a reduction
catalyst and an oxidation catalyst. The first uses a
mix of platinum and rhodium to pull oxygen atoms
away from nitric oxide, creating pure, benign
nitrogen. The oxidation catalyst (platinum and
palladium) then combines oxygen from the reduc-
tion stage with the exhaust’s carbon monoxide to
convert it into far-less-dangerous carbon dioxide.
It also oxidizes unburned hydrocarbons to create
water vapor and carbon dioxide.
Catalytic converters generally house one to two
grams of rhodium and up to seven grams each of
palladium and platinum. Though all three metals
dropped from a peak price in early 2021, at press
time they still command $369, $57, and $42 per
gram, respectively. Mounted to the exhaust pipe
without protection, often near the rear bumper,
cats are an easy target.
Higher-clearance vehicles and hybrids are at
a much higher risk of having their catalytic con-
verter stolen. With a truck or SUV, there’s more
room for thieves to reach underneath. And a
hybrid’s electric assistance lowers the stress on
the internal combustion engine, leaving more pre-
cious metals intact. Earl Black, a mechanic at our
local Meineke Car Care Center in eastern Pennsyl-
vania, says that he commonly sees Toyota hybrids
and Honda crossovers with missing cats.
Many auto insurance companies and repair
shops recommend engraving your license plate
number and VIN onto the cat’s exterior, making the
part identifiable to law enforcement if found. How-
ever, many salvage shops say they accept just about
every cat regardless of what may be scratched onto it.
The NICB also suggests parking in well-lit areas—a
motion-sensing floodlight next to your driveway
is a great start. But that might not be enough, says
mechanic Wade Hughes of Sun Devil Auto in Sun
Lakes, Arizona. One of his customers reported hav-
ing their catalytic converter stolen in broad daylight
while parked in a crowded grocery store lot.
Catalytic converter locks and shields provide
far greater security. Most locks surround the
cat with a steel cage secured to your frame, and
shields seal off the area around the converter.
Both are straightforward solutions, and although
no device can offer absolute protection, these turn
thieves’ easy money into enough of a pain that
they’ll look elsewhere.
If your catalytic converter is stolen, call the police
and your insurance company to report the theft,
and then drive straight to a repair shop. Operating
a vehicle without a cat is not only incredibly loud but
can also lead to a hefty fine in most states.
Following a theft, many drivers will opt to
replace the original cat with a cheaper aftermar-
ket alternative. However, Black says a factory cat
is generally more efficient, and aftermarket ver-
sions can often trigger engine error codes that delay
the repair and drive up the labor cost. Most repair
shops can also install protection systems (like
those below) during the replacement process.BEST
CATALYTIC
CONVERTER
LOCKS/
SHIELDS
LOSTAR CATALYTIC
CONVERTER SHIELD FOR
TOYOTA PRIUS
The Toyota Prius is one of the most
common vehicles to roll into a shop
with its cat missing. This Prius-specific
aluminum shield bolts to the underside
of the car to block access. $47 to $
(depending on model year)CATCLAMP CATALYTIC
CONVERTER CAGE
Cages fit most vehicles.
CatClamp’s model wraps its
¼-in-thick stainless-steel
wire rope around the cat and
loops around the chassis to
add another roadblock for
crooks. $CAT SECURITY SHIELD
This shield wraps around the cat
itself, making it more inaccessible
to thieves than a cage. Cat Security
makes shields for the Honda Element
as well as Toyota vehicles (Prius,
Tundra, Tacoma, Sequoia), along
with the Chevrolet City and the
Nissan NV200. $16 March/April 2022
Cars &
(^4) Trucks
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