P04EA
EVAP System Small Leak Detected - Fuel Tank Side.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 4
- AreaAuxiliary emission controls
- EA
- FaultThe specific fault in that area
What it means
P04EA means the evaporative emission (EVAP) system has a small leak on the fuel tank side of the system, between the tank and the purge or vent valves. The control unit runs a leak test by sealing the system and applying vacuum or pressure, and it saw the pressure change faster than expected for a small hole, roughly pinhole size. The exact test method and the point where the system is split into tank side and canister side depend on the vehicle.
Symptoms
- Malfunction indicator lamp on
- Smell of fuel around the car, particularly after parking
- Difficulty filling the tank, with the pump clicking off early
- Usually no change in driveability
- Other EVAP codes stored alongside it, or the car failing an emissions check
Possible causes
- Fuel filler cap loose, missing, damaged or the wrong type, or with a worn seallikely
- Cracked, perforated or perished EVAP hoses or pipes on the tank side, or loose connections and quick-release fittingslikely
- Leaking filler neck, filler neck seal or corroded filler pipepossible
- Leaking fuel tank pressure sensor seal or fuel tank pressure sensor faultpossible
- Leaking tank seal, fuel pump or sender flange seal, or rollover valvepossible
- Vent or purge valve leaking or sticking partly open, if the vehicle's test treats this as a tank side leakpossible
- Cracked or damaged fuel tank or charcoal canisterrare
How to diagnose
- Read the stored codes and freeze frame data, noting fuel level and temperature when the fault set, and check for other EVAP or fuel system codes.
- Check the fuel filler cap is fitted, tightens properly and is the correct type, and inspect its seal and the filler neck sealing surface.
- Visually inspect the tank side EVAP hoses, pipes, clips and connectors for cracks, splits, chafing, corrosion and poor fitment.
- Check the connectors and wiring to the tank pressure sensor and the EVAP valves for damage, corrosion and water ingress.
- Use the scan tool's live data to check the tank pressure sensor reading against expected values and its response when the valves are operated, following the manufacturer's procedure.
- Command the purge and vent valves where supported and check they open, close and seal correctly.
- Carry out a smoke test of the EVAP system at a low, safe pressure, following the manufacturer's procedure, to find the leak, taking care around fuel vapour.
- After repair, clear the code and run the EVAP monitor drive cycle or test to confirm the fix.
How to fix
- Replace the fuel filler cap with the correct one if it is damaged, worn or the wrong type.
- Replace leaking or damaged EVAP hoses, pipes, clips or connectors.
- Repair or replace the filler neck or filler neck seal.
- Replace the tank pressure sensor, its seal or the faulty vent or purge valve if testing shows it leaks or is faulty.
- Replace the fuel pump or sender flange seal, rollover valve or other leaking tank seals.
- Repair or replace the fuel tank or canister only if confirmed damaged.
Can I keep driving?
The car is normally safe to drive and this is unlikely to cause damage, but book it in soon. Fuel vapour escaping is bad for the environment and the car may fail an emissions test. If you can smell strong fuel or see liquid fuel leaking, stop driving and have it checked straight away.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.