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 lights
Dashboard lights that may come on with this code.
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
- Switch the engine off and let it cool, then visually check the lines, fittings, fuel rail and pump for fuel.
- On a scan tool, watch desired and actual pressure while running, and note how fast pressure drops after shutdown.
- Have an injector return-flow test done to find a leaking injector.
- Check the pressure relief valve and its return line for leakage.
- Confirm fuel level, that the system is free of air, and that the pressure sensor reading makes sense.
How to fix5
- Replace the leaking high-pressure line or fitting; many manufacturers require new lines once they have been removed rather than retightening them.
- Replace any injector whose return flow exceeds the allowed limit.
- Replace the pressure relief valve if it leaks.
- Repair or replace the high-pressure pump or regulator if the leak comes from them.
- 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.
In the Saudi market: SAR 150–5,000 (≈ USD 40–1,330)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
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
Can I drive with this code?
It is not advised. Leaking fuel near hot engine parts can start a fire, and the pressure loss can stall the engine while driving. Have the car towed to a workshop.
How can I look for the leak safely?
Inspect with the engine off and cooled down, and never put your hand near a leak while the engine runs, because a high-pressure fuel spray can pierce the skin and cause serious injury.
What is the difference between P0093 and P0094?
P0093 means a large leak detected quickly, while P0094 means a small leak. The causes are similar, but a large leak is more dangerous and calls for stopping the car right away.
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