P0468 Purge Flow Sensor Circuit High Input

Diagnostic trouble code P0468 indicates that the evaporative emissions (EVAP) system is detecting a high input signal from the purge flow sensor circuit. This code is typically caused by a faulty purge flow sensor, but can also be caused by wiring issues or a problem with the powertrain control module (PCM).

Here are the steps to diagnose and repair the issue:

1. Check the wiring and connectors for damage, wear, or corrosion. Repair or replace as necessary.
2. Check the resistance of the purge flow sensor. Compare the reading to the manufacturer's specifications. If it is outside of the specified range, replace the sensor.
3. Check the power and ground circuits to the purge flow sensor. Use a multimeter to test for voltage and continuity. Repair or replace as necessary.
4. Check the PCM for a software update that may address the issue. If an update is available, follow the manufacturer's instructions to install it.
5. If the issue is not resolved after following the above steps, replace the PCM.

It is recommended to have a professional mechanic perform these steps to properly diagnose and repair the issue.