Hydrocarbon (HC) is basically raw fuel (gasoline). The number one cause a
car will produce high HC is a defective ignition system. During the
combustion process any number of engine conditions can cause high
Hydrocarbons. Sparkplugs and spark wires are constantly exposed to high
temperatures and high voltages. You must ensure your engine's ignition
system is functioning properly, by inspecting all the sparkplugs and their
wires. If any of the plugs look worn out or have excessive carbon build-up
you must replace them. The distributor cap should also be inspected for
cracks or excessive carbon deposits. If it appears that the cap may be
faulty, you will need to replace it as well.
Assuming all other emissions measurements are within limits; CO, NOx, O2 and
CO2, your vehicle's HC fault will be fixed with an inspection and
replacement of the ignition sparkplugs, wires, distributor cap and rotor.
The ignition coil should be the last component in the ignition system to
require replacement, however its inspection will be required as well.
