P0191 is the Fuel rail pressure sensor circuit performance.
Possible causes are :
1. High fuel pressure.
2. Low fuel pressure.
3. Faulty FRP sensor.
4. Excessive resistance in the circuit.
5. Vacuum leaks.
6. Low or no fuel.
There are quite a number of cases whereby the problem is resolved by replacing the fuel pump. Before doing that, test the fuel pressure, at idle, under full acceleration and highway driving. If the pressure is not consistent, quite lilely you have a faulty fuel pump. You mentioned replacing the fuel filter, I understand some models have a double filter, were both replaced?
Recheck the filter to see if it is dirty, hope it is not caused by too much dirt in the fuel tank.
P0308 is a misfiring with cylinder # 8. If it is only this particular cylinder that is misfiring, you would need to check the ignition coil, fuel injector and spark plug.
Monday, March 19th, 2012 AT 5:47 PM