Powertrain, generic · Auxiliary emission controls

P0466 EVAP Purge Flow Sensor Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. A purge flow sensor – a heated thermistor in the purge line between purge valve and intake manifold, as described in a Ford patent – measures purge flow directly for the CARB purge monitor. Today indirect methods (fuel trim, tank vacuum) have largely replaced it; no manufacturer document available to us uses these codes. P0466 means the signal does not fit the purge valve state – the Ford patent judges the voltage difference between 100 % and 0 % purge duty against a calibrated value. The purge flow monitor can then not be evaluated.

Likely causes

Sensor dirty or sluggish (charcoal dust, fuel deposits)
Purge line blocked or purge valve sticking
Hose leaking ahead of the sensor

Symptoms

  • Check engine light on
  • EVAP readiness not set, emission inspection not passed
  • No change in driving

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–250
Time0.3–1.5 h

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

Parts involved

evap purge flow sensorpurge linesensor wiringengine control module

Related codes

P0465P0467P0468P0469P0441

References: law.cornell.edu, patents.google.com, patents.google.com.