Code Definition

P008B — Low Pressure Fuel System - Pressure High

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P008B

P008B is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P008B is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a signal or supply voltage higher than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P008B is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

Direct injection petrol and common rail diesel engines run a two stage fuel system, with an in tank electric lift pump supplying the low pressure side which then feeds a camshaft driven high pressure pump. A low pressure fuel sensor reports supply pressure to the Engine Control Module (ECM), which on most modern applications varies pump speed through a fuel pump control module to hold that pressure at a commanded target, commonly somewhere between 350 and 650 kPa depending on the application. DTC P008B is set when the measured low pressure side reading exceeds the commanded target by more than...

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