Ford 1998 Crown Victoria Owner's Manual page 135

The scheduled maintenance items listed in the "Service Guide" are
essential to the life and performance of your vehicle and to its emissions
system.
If other than Ford, Motorcraft or Ford-authorized parts are used for
maintenance replacements or for service of components affecting
emission control, such non-Ford parts should be equivalent to genuine
Ford Motor Company parts in performance and durability.
Do not park, idle, or drive your vehicle in dry grass or other dry
ground cover. The emission system heats up the engine
compartment and exhaust system, which can start a fire.
Lumination of the charging system warning light, "Check Engine" light or
the temperature warning light, fluid leaks, strange odors, smoke or loss
of oil pressure, could indicate that the emission control system is not
working properly.
If you smell exhaust fumes of any kind inside your vehicle, have
the dealer inspect and fix your vehicle immediately. Do not drive
if you smell exhaust fumes. These fumes are harmful and could kill
you.
Do not make any unauthorized changes to your vehicle or engine. By
law, vehicle owners and anyone who manufactures, repairs, items, sells,
leases, trades vehicles, or supervises a fleet of vehicles are not permitted
to intentionally remove an emission control device or prevent it from
working. Information about your vehicle's emission system is on the
Vehicle Emission Control Information Decal located on or near the
engine. This decal identifies engine displacement and gives some tune up
specifications.
Please consult your "Warranty Guide" for complete emission warranty
information.
Readiness for inspection/maintenance (I/M) testing
In some localities, it may be a legal requirement to pass an I/M test of
the on-board diagnostic (OBD-II) system. If your "Check Engine/Service
Engine Soon" light is on, refer to the description in the Warning Lights
and Chimes section of the Instrumentation chapter. Your vehicle may
not pass the I/M test with the "Check Engine/Service Engine Soon" light
on.
Maintenance and care
135