External fuel leak from a high-pressure fuel line, fitting, rail or injector seal; Leaking or stuck-open injector letting fuel pressure bleed away; Faulty fuel pressure regulator or pressure control valve that cannot hold pressure; Worn or failing high-pressure fuel pump unable to build pressure; Low-pressure supply fault such as weak lift pump, blocked filter or restricted feed starving the high-pressure pump; Faulty fuel rail pressure sensor giving false readings; Wiring or connector fault on the pressure sensor or regulator circuit.

P0093

Fuel System Leak Detected - Large Leak.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
0: AreaFuel and air metering, auxiliary emission controls
93: FaultThe specific fault in that area

What it means

P0093 means the engine control unit has detected a large leak in the high-pressure side of the fuel system. It typically sets when the measured fuel rail pressure cannot be built or held at the commanded level, or drops far faster than expected, despite the pump and pressure control being driven to compensate. The exact strategy used to detect the leak varies by engine and fuel system design.

Symptoms

Engine cranks but is long to start or does not start
Loss of power or poor acceleration
Rough running, misfires or stalling
Smell of fuel around the engine bay or visible fuel leak
Malfunction indicator lamp on, possibly with limp mode
Hesitation under load

Possible causes

External fuel leak from a high-pressure fuel line, fitting, rail or injector seallikely
Leaking or stuck-open injector letting fuel pressure bleed awaylikely
Faulty fuel pressure regulator or pressure control valve that cannot hold pressurepossible
Worn or failing high-pressure fuel pump unable to build pressurepossible
Low-pressure supply fault such as weak lift pump, blocked filter or restricted feed starving the high-pressure pumppossible
Faulty fuel rail pressure sensor giving false readingsrare
Wiring or connector fault on the pressure sensor or regulator circuitrare

How to diagnose

Read all stored codes and freeze frame data, noting rail pressure, engine speed, load and temperature when the fault set
Look carefully for fuel smell, wet patches or staining around the rail, lines, fittings, injectors and pump, with the engine off and cool
Inspect wiring and connectors to the rail pressure sensor, pressure regulator and pump for damage, corrosion or poor contact
Check low-pressure fuel supply pressure and volume against the manufacturer's specification for that engine
Monitor actual versus commanded rail pressure on live data during cranking, idle and a load test
Check the rail pressure sensor reading with the key on and engine off against a known good reference
Carry out a pressure hold or leak-down test as per the manufacturer's procedure for that fuel system
Perform injector leak-off or balance tests where the engine type allows

How to fix

Repair or replace any leaking fuel line, fitting, rail or seal, using the correct parts and torque settings
Replace leaking or stuck injectors as diagnosed, following the manufacturer's coding or adaptation procedure if required
Replace a faulty pressure regulator or pressure control valve
Replace the high-pressure pump if it cannot reach specified pressure after supply faults are ruled out
Restore the low-pressure supply by replacing the lift pump or fuel filter as required
Repair damaged wiring or connectors, or replace a faulty rail pressure sensor

Can I keep driving?

High severity

Do not keep driving the car if you can smell fuel or see a leak, as a high-pressure fuel leak is a serious fire risk. If the engine will not run properly or is in limp mode, have it recovered and inspected before further use.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.