What does it mean?
On vehicles equipped with Evaporative Emission Control Systems, also known as EVAP, the engine draws excessive fuel vapors from the gas tank that would otherwise be released into the atmosphere.
The fuel vapor is routed via a vacuum line to the engine intake, and the purge valve/solenoid measures the desired amount of fuel vapor, controlled by the Powertrain Control Module (PCM) or Engine Control Module (ECM). The PCM/ECM monitors the voltage to the purge control valve and detected no voltage change with the purge valve activated.
Note: This code is similar to P0443 and P0445 codes.
Symptoms
Symptoms of a P0444 trouble code may include:
Check Engine Light illuminated (Malfunction Indicator Light on)
Slightly reduced fuel economy; this will not affect engine performance
Potential Causes
Causes
of this DTC may include:
Loose or disconnected wiring harness
Open circuit in the engine wiring harness
Open circuit in the purge control solenoid
PCM/ECM malfunction
Diagnostic Steps
for P0444 DTC
Engine Wiring Harness – Check all connectors to ensure they are properly plugged in, look for loose or damaged wires. Typically, the purge control valve is powered by the battery and triggered on and off with a duty cycle via the PCM/ECM. Using the manufacturer’s wiring diagrams, identify the type of circuit used and check for battery voltage with the key on/engine off on the power side of the purge control solenoid connector using a Digital Volt-Ohm Meter (DVOM) set to the volts scale. If no battery voltage is present, trace the wiring and determine the cause of the voltage loss.
Test the continuity on the control side of the wiring harness after unplugging the solenoid plug from the purge control valve and PCM wiring harness. Identify the correct wire at the PCM and the control valve harness and check continuity using the ohms scale on the DVOM. If excessive resistance is found, repair the circuit. If there is no continuity in the circuit, check all connections for damaged wiring, loose pins, or disconnected harnesses and repair the circuit.
Purge Control Solenoid – Check continuity at the purge control solenoid connector pins after removing the harness plug using the DVOM set to the ohms scale. Verify that the resistance meets the manufacturer’s specifications. If no continuity is present, suspect that the solenoid is open internally and replace the part with a known good unit.
PCM/ECM Malfunction – Since the EVAP is only activated under certain driving conditions, it will be necessary to monitor the EVAP control operation using a capable advanced scan tool and perform a road test under the required driving conditions to activate the EVAP system. Some advanced scan tools have an internal test to manually activate the EVAP system. Verify that the PCM/ECM is commanding the EVAP system. If the system is operating correctly, it will be necessary to probe the PCM/ECM wiring harness connector using a graphing multimeter or oscilloscope with a duty cycle function, with the positive lead on the purge control valve pin and the negative lead connected to a known good ground. The duty cycle should match what is commanded by the PCM/ECM during EVAP operation. If no duty cycle is present, the PCM/ECM may be faulty.
Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0445 – P0446 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456