Purge Flow Sensor Circuit Low Input
The ECU detected that the purge flow sensor is sending a voltage signal that's too low, like a weak radio station. This usually means the sensor itself is failing or its wiring connection is corroded.
The ECU monitors the purge flow sensor voltage to ensure the charcoal canister is purging fuel vapors correctly into the engine. The sensor should output a voltage within a specified range; when it drops below the minimum threshold, the ECU logs this fault. A low signal typically indicates sensor degradation, open circuits, or poor electrical connections.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Purge Flow Sensor Voltage | 0.5-4.5 volts | Below 0.5 volts |
| Sensor Signal Frequency/Response | Proportional to purge airflow | Insufficient or no signal variation |
Code P0468 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0468 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.