P0093: ECU-detected large fuel loss; distinguish external leakage, internal loss and supply problems.
Meaning, symptoms, causes and checks
The ECU infers a large fuel loss from fuel-system behavior or regulation effort. It does not alone confirm a visible leak; internal loss, inadequate supply or incorrect information may be involved.
Affected system: Powertrain
Symptoms
- Reduced power, protective mode or engine shutdown.
- Hard starting; possible fuel odor or wetness if an external leak exists.
Possible causes
- External loss or excessive internal return through injectors/control components, depending on design.
- Inadequate supply, metering problem or implausible pressure feedback requiring differentiation.
What to check
- Save failure conditions and check the OEM definition; record requested/reported pressure and regulator command.
- With the engine stopped, visually inspect accessible lines for wetness/damage; visible fuel requires stopping use until repaired.
- Check low-pressure supply, filter and air ingress by the engine-specific method.
- Validate sensor plausibility, then obtain OEM injector-return and regulation tests; do not assume a ruptured pipe.
- Never loosen pressurized common-rail lines or search for leaks by hand; follow depressurization instructions before work.
Also written as: P0093-00, P009300, PO093 (some scan tools add the fault-type byte, e.g. -00).