Fuel and air

P0093 — Fuel System Leak Detected – Large Leak

Severity: high Do not drive

What P0093 means

The engine control module compares actual fuel rail pressure with the target value. P0093 is set when pressure drops too fast or can't build up, which indicates a large leak in the fuel system. A faulty pressure sensor can cause it too, but a real leak must be ruled out first.

Symptoms

  • Check Engine light on
  • Strong fuel smell around the vehicle
  • Hard starting or no-start
  • Engine stalling
  • Loss of power or limp mode
  • Rough idle

Possible causes

  1. Leaking high-pressure fuel line or fuel rail
  2. Faulty fuel pressure sensor or its circuit
  3. Leaking or damaged injector, failed injector O-ring
  4. Failing fuel pump or lift pump
  5. Faulty fuel pressure regulator
  6. Damaged wiring or connectors: corrosion, short, open
  7. Loose or unplugged fitting on the fuel rail after recent service
  8. Cracked fuel tank or fuel line

How to diagnose

  1. Scan for codes and freeze frame data, and note any other fuel-related codes
  2. Inspect the engine bay and underbody for fuel traces, keeping sparks and flames away
  3. Check fittings and seals at the fuel rail, injectors and lines, especially after recent work
  4. Compare the sensor's rail pressure reading with a mechanical gauge
  5. Test the pressure sensor's power, ground and signal wires and inspect the connectors
  6. Test fuel pump pressure and volume
  7. Check pressure hold after shutdown to find a leaking injector or regulator
  8. After repair, clear the code and check for leaks with the engine running

Common fixes

  • Replace or reseal damaged fuel lines and high-pressure connections
  • Replace injector O-rings or leaking injectors
  • Replace the fuel pressure sensor
  • Replace the fuel pump or pressure regulator
  • Repair the wiring and connectors to the sensor or ECM

Questions and answers

Can I drive with P0093?

No. A large fuel leak can cause a fire, and the engine may stall while driving. Have the car towed.

Can P0093 be caused by a bad sensor instead of a leak?

Yes, a faulty pressure sensor or wiring can report false pressure. Still, you should not assume that until a leak is ruled out by inspection and a pressure test.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.