Powertrain, generic · Fuel and air metering, auxiliary emission controls
P0094 Fuel System Leak Detected - Small 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. P0094 is typically detected when rail pressure drops too fast during overrun with injection cut off, or when more pump delivery than expected is needed at idle. Possible leaks are injectors with too much leak-off, fittings or relief valves; internal leakage can dilute the engine oil with fuel, so a rising oil level is a warning sign.
Likely causes
Injector with excessive leak-off
High-pressure fitting slightly leaking
Pressure relief valve leaking
Engine control software (manufacturer updates exist)
Symptoms
- Check engine light on
- Long cranking
- Rising engine oil level from fuel dilution
- Slight loss of power
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.
Parts involved
fuel injectorshigh pressure fuel linesfuel pressure relief valveengine oil
Related codes
References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.