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The N54 and N52KP meet ULEV II requirements for 2007. There are not many
changes to the emission
systems on these engines. The N54 engine has 2 underbody catalysts in addition
to the "near engine" catalysts
already in use from the N52.
The N51 engine, however, is a SULEV II compliant engine which
Fuel systems need to be checked for proper fuel pressure as well as
sufficient volume. When diagnosing fuel
system complaints, you must take into account the type of fuel system and how
the fuel is delivered to the
engine.
Malfunctions in the fuel system can cause driveability complaints which in