P0466
EVAP Purge Flow Sensor Circuit Range/Performance.
- 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
- 66
- FaultThe specific fault in that area
What it means
P0466 is the generic code for a range or performance fault in the EVAP purge flow sensor circuit. The engine control unit compares the purge flow sensor signal with what it expects while the purge valve is commanded open or closed, and has seen a reading that is implausible or does not respond correctly. Many vehicles do not have a dedicated purge flow sensor, so how the signal is measured depends on the make, model and engine.
Symptoms
- Engine warning light on
- Difficulty restarting after refuelling or rough idle just after starting
- Fuel smell around the car or near the fuel filler
- Slightly poorer fuel economy
- Failed emissions test or EVAP monitor not ready
- Fuel filler cap warning message on some models
Possible causes
- Purge control valve stuck open, stuck closed or leaking internallylikely
- Faulty purge flow sensor or related pressure sensor giving a drifting or out-of-range signallikely
- Damaged, chafed or corroded wiring or connector in the sensor or purge valve circuitpossible
- Cracked, blocked or disconnected EVAP hoses or pipes between the canister, valve and intakepossible
- Blocked or saturated charcoal canister, or a restricted vent pathpossible
- Loose, damaged or incorrect fuel filler cap causing abnormal system pressurepossible
- Engine control unit fault or outdated software calibration, where the manufacturer has documented itrare
How to diagnose
- Read all stored and pending codes and freeze frame data, noting fuel level, engine temperature and load when the fault set, and look for other EVAP codes.
- Check the fuel filler cap is fitted, sealing properly and is the correct type, then inspect the filler neck.
- Visually inspect the purge valve, flow sensor, wiring, connectors and EVAP hoses for damage, chafing, corrosion, splits or loose fittings.
- Check live data for the purge flow or related sensor signal with the engine off, at idle and with the purge valve commanded on and off, and compare it with the manufacturer specification.
- Test the purge valve for correct clicking, coil resistance and whether it holds vacuum when closed and flows when energised.
- Check the sensor supply voltage, earth and signal wiring for continuity, shorts and voltage drop.
- Smoke test the EVAP system to find leaks, and check the canister and vent path for blockage.
- Check for manufacturer service bulletins or software updates for your model and engine.
How to fix
- Replace the purge control valve if it sticks or leaks.
- Replace the purge flow sensor or related pressure sensor if its signal is out of range or does not respond.
- Repair or replace damaged wiring and connectors, and clean up any corrosion.
- Replace cracked, blocked or disconnected EVAP hoses and pipes, and refit the fuel filler cap or replace it if faulty.
- Replace the charcoal canister or clear the vent path if it is blocked or saturated.
- Apply a manufacturer software update only if a bulletin confirms a calibration fault for your vehicle.
Can I keep driving?
The car is normally safe to drive in the short term and this is not likely to cause immediate engine damage. Book it in soon, particularly if you can smell fuel, as a stuck-open purge valve can cause hard starting or rough running.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.