If the measured value is greater than the nominal value + 0.2 bar:

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

Switch off engine and then observe measured value.
If the measured value drops to the nominal value, the cross-sections in the fuel return line are contracted or clogged.
Check the fuel lines for kinks.
If no kinks are visible:
Replace return lines.
If the measured value remains too high, the pressure regulator is most probably faulty.

CAUTION: With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could escape under pressure!
- As a precaution, have a cleaning cloth ready and collect and dispose of any escaping fuel.
- Replace the return line but not the pressure regulator.