Powertrain, generic · Fuel and air metering, auxiliary emission controls

P0093 Fuel System Leak Detected - Large Leak

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

A leak in the high-pressure fuel system is not measured directly but inferred from a pressure and volume balance. P0093 means the pump is already delivering at its limit and rail pressure still stays well below target. The leak can be external (line, rail) or internal (injector return, relief valve). An external leak is a fire hazard: stop the engine and inspect it.

Likely causes

High-pressure line or rail fitting leaking
Injector with excessive leak-off
Pressure relief or control valve leaking
Weak pump or low-pressure supply mistaken for a leak

Symptoms

  • Check engine light on
  • Loss of power or reduced power mode
  • Long cranking
  • Fuel smell or visible leak

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

  1. Stop driving if you smell fuel
  2. Inspect high-pressure lines and fittings
  3. Check injector return quantities on diesels

Parts involved

fuel injectorshigh pressure fuel linesfuel railfuel pressure relief valvehigh pressure fuel pump

Related codes

P0094P0087P0089P0190

References: law.cornell.edu, gsi.ext.gm.com.