P0468 - Fuel Pump Purge Control Valve Circuit High
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
Diagnostic Trouble Code (DTC) P0468 is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal in the fuel pump purge control valve circuit. The ECM monitors the circuit using duty-cycle signals (PWM). If the voltage remains high when the ECM attempts to ground the circuit to activate the valve, it indicates a short to voltage or an open circuit. This fault disrupts the evaporative emission control logic, potentially affecting air-fuel ratios during purge cycles.
Possible Causes
Short to voltage (12V) in the wiring harness for the purge control valve
Faulty purge control valve (internal electrical short)
Corroded connectors or loose pins in the ECM connector
Internal fault in the Engine Control Module (ECM)
Symptoms
Recommended Solution
- Visual Inspection: Check wiring harness and connectors near the fuel tank for chafing, corrosion, or heat damage.
- Multimeter Test: Disconnect the valve and measure solenoid resistance (typically 20-50 Ohms). Measure voltage at the connector with ignition ON; the control side should not have permanent 12V.
- Functional Test: Use a scan tool to perform a bi-directional active test of the purge valve. Listen for a physical clicking sound.
- Component Replacement: Replace the purge control valve if internal resistance is out of spec or if it fails the functional test.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0468 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.