P008A means the engine control module measured pressure in the low-pressure fuel system, between the tank and the high-pressure pump, below its target. Its pair is P008B (too high). It is distinct from P0087, which is the high-pressure rail; on engines with sensors on both sides, the two codes together say where to start.
Severity: moderate. Can you keep driving? Carefully, to a shop. Low supply pressure starves the high-pressure pump, and on diesels a starved high-pressure pump wears quickly and can shed metal into the injectors. Expect hard starting and low power; on some trucks the engine speed is limited. Do not run the tank low.
What the truck makers say
- Mack Trucks, US13 to US17 emissions engines (bulletin GDC18-059, February 2020): the repair instruction for P008A is a fuel pressure sensor replacement, with a note that reads in effect: check that the fuel filter is not clogged and has been replaced on schedule before replacing the sensor. The possible causes it lists: fuel filter, fuel system, overflow valve, fuel pump, engine fuel pressure sensor, air in the fuel system.
- Volvo Trucks, US13 to US20 emissions (RD19-002, April 2019, updated 2024): when P008A and P0087 are both active at the same time, the instruction is to replace the primary and secondary fuel filters, with a warning that the newer filter housings need the deep-groove end cap and the wrong filter neither fits nor seals and can shed metal debris. Possible causes for P008A: clogged filter, low fuel level, air in the system, tank ventilation not working, fuel pump, pressure sensor.
- Alfa Romeo, 2017 to 2018 Giulia and Stelvio 2.0 L and 2.9 L: bulletin 18-001-18 announced a remedy for P008A tied to low-pressure fuel pump failures, and a 2024 federal investigation examined those pumps; a 2021 Stelvio flash bulletin also lists P008A among codes addressed by software and an oil vapor recovery tube.
Causes, in the order they are found
A clogged fuel filter or one past its interval.
Low fuel level, or a tank vent that does not admit air, letting the tank pull a vacuum.
Air in the system from a loose fitting, a cracked line or a filter housing not sealed.
A weak lift pump (in-tank or engine-mounted) or a failed overflow or regulating valve.
A restricted line between the tank and the engine.
The pressure sensor, when the measured pressure is normal and the code persists.
The module, last.
A diagnostic order
- Check fuel level and the filter service history. Replace the filter if it is due; on Volvo engines with both codes active this is the whole repair.
- Look for air: bubbles in a clear line, a fuel smell at fittings, a filter housing seal.
- Measure low-side pressure with a gauge at the specified test point, engine idling and under load, against the specification.
- Compare the gauge with the sensor's reading on the scan tool. Gauge normal and sensor low means the sensor or its circuit; both low means supply.
- Test the lift pump for output and current draw, and check the overflow or regulating valve.
- Check the tank vent by loosening the cap while watching pressure.
- Replace the sensor only after the gauge disagrees with it, then clear and verify under load.
Frequently asked questions
Can I drive with a P008A code?
Carefully, to a shop, and not with a low tank. Low supply pressure starves the high-pressure pump, which on a diesel is an expensive part to damage. Expect hard starting and low power until it is fixed.
What is the difference between P008A and P0087?
P008A is the low-pressure side, from tank to high-pressure pump. P0087 is the high-pressure rail. Both at once on a Volvo or Mack engine usually means the filters; P0087 alone with normal supply pressure means the high-pressure pump or rail; see P0087.
Is P008A the fuel pressure sensor?
Sometimes, but the truck makers' own instructions put the filter first, and a gauge reading normal while the sensor reads low is the only evidence that justifies replacing the sensor.
How much does it cost to fix P008A?
Filters are a routine maintenance cost. A lift pump is a moderate part, more with tank access. A sensor is inexpensive. The expensive outcome is a high-pressure pump damaged by running starved, which is why the filter comes first.
Related codes
- P008B: low pressure fuel system pressure too high.
- P0087 / P0088: rail pressure too low or high.
- P0190 to P0194: rail pressure sensor circuit.
- P0230 to P0232: fuel pump primary circuit, the lift pump's electrical side.
The code number itself tells you the family and the domain; how to read an OBD2 code number explains what each character means and why the A in P008A is a hexadecimal digit.