DTC P008A00 – Low Fuel Pressure (Low Pressure System).
This code is common on diesel and GDI petrol engines with low-pressure supply pumps.

✅ DTC P008A00 – Low Fuel Pressure System (When Engine Running)

Meaning

The ECM detects that the low-pressure fuel system (from tank to high-pressure pump) is below the required threshold.
If pressure is too low, the high-pressure pump cannot deliver enough fuel, causing:

Hard starting

Long cranking

Low power

Stalling

Hesitation on acceleration

✅ Common Causes

1. Low-pressure fuel pump (in-tank pump) weak/failing

Very common cause.

2. Fuel filter clogged

Restriction reduces pump output.

3. Fuel supply line restriction

Pinched lines

Debris

Rust in metal lines

4. Fuel pump relay or wiring fault

Poor ground

Loose connector

Corroded relay contacts

5. Fuel tank contamination
Water

Mud/dust

Bad diesel/petrol

6. Fuel pressure sensor (low side) faulty

Incorrect readings can trigger P008A00.

7. High-pressure pump over-pulling

If HP pump is failing, it draws excess suction → low inlet pressure.

🔧 Step-by-Step Diagnostic Guide

1. Check live data (very important)

Look at:

Low-side fuel pressure

Fuel pump command % (PWM)

Fuel pump current (A)

Fuel temperature

Desired vs actual low pressure

Typical diesel low-side pressure:

3.5–5 bar (may vary by make)

If pressure is much lower → proceed.

2. Inspect fuel filter

Remove and check for dirt/water contamination

If old → replace first (quick, cheap fix)
Clogged filters cause most P008A cases.

3. Test the in-tank fuel pump

Check:

Voltage at pump connector

Ground continuity

Pump current draw

Sound (weak/uneven is bad)

If pump runs but pressure is still low → pump is weak → replace pump module.

4. Check fuel lines

Look for:

Kinks

Squashed plastic pipes

Leaks or air entry on diesel systems (transparent lines make this easy)

Air bubbles = suction leak before pump.

5. Test fuel pressure sensor

If readings in live data are erratic or do not change with engine load → sensor may be faulty.

6. Inspect HP pump for excessive suction

If high-pressure pump is internally worn, it pulls extra fuel → low feed pressure.

Test:

Disconnect HP pump inlet (if system allows)

Check low pressure without load
If pressure is normal → HP pump is suspect.

🛠️ Quick Tips for Mechanics

Low side pressure should rise when revving; if it drops → weak pump.

If fuel pump duty cycle is 80–100% but pressure is low → pump is failing.

If duty cycle is low (<20%) and pressure is low → wiring/relay/fuse issue.

🚗 Fix Summary

Cause Fix

Clogged fuel filter Replace filter
Weak in-tank pump Replace fuel pump module
Line blockage/kink Repair / replace line
Bad pump relay/wiring Repair wiring / replace relay
Faulty low-pressure sensor Replace sensor
High-pressure pump fault Replace high-pressure pump

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