Circuit Description In a direct fuel injection system, fuel is taken from the fuel tank by the low-pressure fuel pump and delivered to the high-pressure fuel pump installed to the cylinder head. The high-pressure pump increases fuel pressure to 5-10 MPa and injects the fuel directly into the cylinders through the fuel injectors. The injectors use a solenoid valve. A sensor installed to the fuel rail measures high pressure in the fuel line. The sensor transmits the data to the ECM. The desired pressure is maintained by the pressure regulator duty output in response to feedback data from the ECM.
Under normal conditions, actual fuel pressure is maintained at a nearly constant level by the pressure regulator control duty. The ECM monitors this pressure relative to the control duty. The pressure must be within preset upper and lower limits. If it is not, there is an abnormality in the high-pressure fuel delivery system. The code data is stored in memory.
Conditions for Setting The DTC
Fuel pressure is below 11-15.4 MPa or above 0-4 MPa (Depends on duty) Engine is running Pressure regulator is closed loop Not during fuel shut off Fuel level is below 13% Ignition voltage is below 10.96 V Baro is below 72 kPa IAT is below -10 °C No DTC's below set: Crankshaft angle sensor (P0336, P0337) Camshaft angle sensor (P0341, P0342, P0346, P0347) High fuel pressure solenoid (P1237, P1238, P1240) High fuel pressure sensor (P1241, P1242) Low-pressure fuel (P1245, P1246) ROM (P0601) RAM (P0604
most of the time this code is due to a faulty high pressure fuel sensor mounted on the fuel rail underneath and hidden by the intake manifold: