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Home >> Saturn >> 1997 >> SW2 Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics >> Diagnostic Trouble Codes >> DTC P0440 &/Or P0443 - EVAP Canister Purge Solenoid Circuit Fault >> Circuit Description

Circuit Description

The Evaporative System (EVAP) draw fuel vapors from the fuel tank into a charcoal canister to be used to meter air/fuel ratio upon request. An EVAP canister purge solenoid is used to control the flow of vapors from the canister to the intake manifold controlled by the PCM. PCM controls the solenoid with a pulse width modulated (PWM) signal. The uses a Generic Field Effect Transistor Driver (GFD) to control the solenoid's ground when certain conditions have been met. The GFD driver has the capability to diagnose if the circuit has opened or shorted and can also monitor if the plunger has actually moved by the electrical diagnostic feedback circuit.

DTC P0440 will set if the PCM determined that the EVAP canister purge solenoid has not moved when engine is off idle, commanded duty cycle is 30-65 percent, or when no MAP, ECT or TP sensor DTCs have been set.

DTC P0443 will set if there is an open, short to battery, short to solenoid coil, or short to ground in the EVAP canister purge solenoid circuit when ignition is on.

EVAP canister purge solenoid is continuously checked for movement when the engine is running and the DTC parameters have been met.

NOTE: If an O2S or EGR related DTC is present, diagnose these DTCs first.
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