Powertrain, generic · Auxiliary emission controls

P0468 EVAP Purge Flow Sensor Circuit High

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. P0468 means the signal voltage is above its upper limit – signal or ground open with a pull-up, or a short to positive. The purge flow monitor can then not be evaluated.

Likely causes

Signal or ground wire open
Sensor faulty
Short to positive

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

P0465P0466P0467P0469P0441

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