The Motor Control Module (MCM) monitors the fuel rail pressure, and when fuel rail pressure deviation is greater than 200 bar higher than requested fuel rail pressure for eight seconds, the MCM sets the code. This fault can occur due to the conditions listed below:

• Faulty fuel rail pressure sensor
• Faulty Quantity Control Valve (QCV)
• Faulty MCM
• Faulty Wiring

1. Turn the ignition ON (key ON, engine OFF).

1. Using DiagnosticLink^® , check for multiple codes. Are additional codes, excluding ACM codes, present along with SPN 157/FMI 18?
   1. Yes; troubleshoot the additional codes first.
   1. No; Go to step 3.

1. Check actual fuel rail pressure (key ON, engine OFF). Is actual fuel rail pressure greater than 5 bar?
   1. Yes; Go to step 4.
   1. No; Go to step 5.

1. Remove the fuel rail pressure sensor and reconnect the sensor to the harness.  Is the fuel rail pressure sensor reading greater than 5 bar with sensor removed from rail?
   1. Yes; replace the fuel rail pressure sensor. 
   1. No; install the removed fuel rail pressure sensor. Go to step 5.

1. Perform the Fuel System Integrity Check (FSIC) test using DiagnosticLink^® .

1. Is the actual fuel rail pressure (ASL001) 200 bar higher than the desired rail pressure (AS098) at any point during the FSIC test?
   1. Yes; replace the quantity control valve.
   1. No; the deviation is less than 200 bar, Go to step 7.

1. Inspect the fuel rail pressure sensor connector and MCM 120-pin connector for corrosion, bent, spread, or damaged pins. Is any damage found?
   1. Yes; replace the damaged component.
   1. No; replace the fuel rail pressure sensor.