Fuel System Leak Detected - Large Leak

What it means

The engine computer has seen a fast drop in fuel pressure that engine fuel use does not explain, so it concluded there is a large leak in the system. This code is most common on high-pressure diesel engines and some direct injection engines. The leak may be external and visible, or internal through the injectors or the pressure relief valve.

Related codes: P0094P0087P0089P0190P0191

Symptoms5

• Strong fuel smell or visible fuel around the engine.
• Severe power loss or limp mode.
• Hard starting or stalling while driving.
• Check engine light on.
• Noticeably higher fuel consumption.

Possible causes6

• External leak from high-pressure lines, their fittings or the fuel rail.
• Internal leak in one or more injectors, or excessive injector return flow.
• Leaking pressure relief valve on the fuel rail, on systems that have one.
• Leak at the high-pressure pump or pressure regulator.
• Air in the system or running out of fuel.
• Faulty fuel pressure sensor giving a false reading (less common).

How to diagnose5

1. Switch the engine off and let it cool, then visually check the lines, fittings, fuel rail and pump for fuel.
2. On a scan tool, watch desired and actual pressure while running, and note how fast pressure drops after shutdown.
3. Have an injector return-flow test done to find a leaking injector.
4. Check the pressure relief valve and its return line for leakage.
5. Confirm fuel level, that the system is free of air, and that the pressure sensor reading makes sense.

How to fix5

1. Replace the leaking high-pressure line or fitting; many manufacturers require new lines once they have been removed rather than retightening them.
2. Replace any injector whose return flow exceeds the allowed limit.
3. Replace the pressure relief valve if it leaks.
4. Repair or replace the high-pressure pump or regulator if the leak comes from them.
5. Bleed air from the system, then clear the codes and confirm pressure holds with no leaks.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when a line or fitting is to blame, rises with injector replacement, and reaches the upper end when the high-pressure pump is replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions