A small leak in the high pressure part of the fuel system
Warning! The fuel system has a very high pressure, up to 2000 bar. The fuel system must be depressurised before any work is performed. The system should always be treated as pressurised, even when the engine is switched off. Wear protective gloves and goggles. For more information on safety when working with the fuel system, see the service information "XPI fuel system" Check for external fuel leaks from the high pressure parts of the fuel system. If no external fuel leaks are visible, continue leak detection in the following order: 1. Check how large the leak is; follow Checking for internal leaks. 2. Check if the safety valve leaks; follow Leak testing the safety valve. 3. Check if the injector leaks; follow Fuel leak test. 4. Troubleshoot the high pressure side according to the instructions, see Workshop manual, 03-00 Fuel and exhaust system assembly, 03:14-01 Fuel system XPI troubleshooting. 5. Troubleshoot the high pressure pump according to the instructions, see Workshop manual, 03-00 Fuel and exhaust system assembly, 03:14-01 Fuel system XPI troubleshooting. To verify that the problem is resolved after step 1-5 are executed and to remove the fault code run "High pressure fuel system leakage workshop test" and follow the instructions.
What you'll see
Engine power may be affected. If leakage is external, fuel leakage around high pressure fuel system components may be observed
System reaction
MI warning lamp MI_C and yellow warning lamp
Diagnostic depth
The fuel pressure in the accumulator drops during engine braking even though no fuel is consumed.
A small leak in the high pressure part of the fuel system