there is no way for the engine ecu on this injection system too tell what
the fuel pressure is, its all pre set.
For the ecu too put up the warning light on,
one the sensors would be detected as faulty by the ecu, ie oc, sc or value
outside of specified limits.
a blocked fuel filter or faulty fuel pump could not do this.
some likly candidates for putting up this light with rough running are the
lambda sensor(most likly) coolant temp sensor, or map sensor.
however there is very little point it guessing what it could be, 1 min on
the diagnostic machine at your local dealer will tell you exactly what to