Technical Description of OBD-II Trouble Code
The pressure in the low-pressure fuel system is too high.
What does that mean?
This generic powertrain diagnostic trouble code (DTC) is applicable to all OBD-II vehicles, including Hyundai, Ford, Mazda, Dodge, and others.
Low fuel pressure systems are commonly used in diesel systems. The injection pump is responsible for providing diesel engines with the high fuel pressures needed to atomize the fuel effectively.
However, the injection pump still requires fuel to be supplied. This is where low fuel pressure pumps/systems come into play. It is crucial for the ECM (Engine Control Module) to closely monitor these conditions. The introduction of air caused by a starved injection pump/injector under load can lead to significant issues. Forced limited power is usually a mode that the vehicle enters to control certain values and prevent further engine damage. Fuel also needs to pass through various filters, pumps, injectors, lines, and connections before reaching the engine, so there are many potential issues. Even small fuel leaks often produce a noticeable smell.
While monitoring numerous other systems and sensors, the ECM has detected a low fuel pressure condition and/or insufficient flow. It is important to consider local fuel conditions as repetitive fill-ups with dirty fuel can contaminate not only the fuel tank but also the fuel pump and other components.
The P008B Low Pressure Fuel System Pressure – Too High code is set when the ECM detects high pressure within the low fuel pressure system.
What is the severity of this DTC?
High fuel pressures can cause future issues in diesel engines. The severity of this code can be considered moderate-high because if you plan to drive your diesel vehicle daily, you need to ensure that your fuel system is functioning properly.
What are some of the symptoms of the code?
Symptoms of a P008B diagnostic code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P008B troubleshooting steps?
Basic Step #1
If there are any leaks, address them immediately. Leaks can cause lower than desired fuel pressures in a closed system, so ensure that the system is properly sealed and not actively leaking. Fuel leaks can be caused by rusted lines, fuel filter gaskets, deteriorated o-rings, and other factors.
Basic Tip #2
Check the fuel filter in your low fuel pressure system. It may be located on the frame rail or close to the fuel tank. If the fuel filter appears to have never been changed or has not been replaced for a while, it should be replaced. Introducing air into a diesel fuel system can be a challenging problem to fix, so follow proper bleeding and filter replacement procedures. Refer to the service manual for specifications and procedures.
Basic Step #3
If possible, locate the fuel injector. It is usually easy to find, but there may be plastic covers or brackets obstructing the view. Ensure that no fittings or connectors are leaking fuel. Common leaks occur around the injector itself (o-ring). Inspect visually for any signs of physical damage or anything that could restrict fuel flow (e.g. kinked line at injector). Particles in the fuel can cause issues due to the small openings. Maintain the fuel system properly by replacing fuel filters and addressing EVAP system maintenance.
