BMW X5: Limp-Home Mode
If a fault is diagnosed in the system, such as e.g. failure of the
high-pressure sensor, the fuel-supply control
valve is de-energized; the fuel then flows via a so-called bypass into the rail.
In the event of HPI limp-home mode, turbocharging is deactivated by an opening
of the wastegate valves.
Causes of HPI limp-home mode can be:
- Implausible high-pressure sensor values
- Failure of the fuel-supply control valve
- Leakage in the high-pressure system
- Failure of the high-pressure pump
- Failure of the high-pressure sensor
![Engine Service Information](images/books/1905/index272(4).png)
Fig. 56: Identifying Limp-Home Mode Diagram
Fuel System Safety
Working on this fuel system is only permitted after the engine has cooled
down. The coolant temperature must
not exceed 40ºC. This must be observed without fail because otherwise there is a
danger of fuel sprayback on
account of the residual pressure in the high-pressure system.
When working on the high-pressure fuel system, take particular care to ensure
conditions of absolute cleanliness
and follow the work sequences described in the repair instructions. Even the
tiniest contaminant's and damage
to the screw connections on the high-pressure lines can cause leaks.
![Engine Service Information](images/books/1905/index273(4).png)
Fig. 57: Identifying Fuel System Safety Label
![Engine Service Information](images/books/1905/index274(4).png)
Fig. 58: Identifying High-Pressure Fuel Lines
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FREON
The refrigerant Freon R12 is used in most BMW automobiles with an air
conditioner up through the 1992
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